Method and apparatus for providing flexible partially etched capacitor electrode interconnect

ABSTRACT

The present subject matter includes a capacitor stack disposed in a case, the capacitor stack including one or more substantially planar electrode layers. The one or more substantially planar electrode layers have an etched surface, an unetched surface, and a grade bordering the etched surface and the unetched surface. Also, the present subject matter includes a lid conforming sealingly connected to the material defining the first aperture. Additionally, the present subject matter includes a feedthrough assembly connected to the capacitor stack and passing through the feedthrough hole and sealingly connected to the material defining the feedthrough hole. In the present subject matter, the one or more substantially planar electrode layers are made by printing a curable resin mask onto the one or more substantially planar electrode layers and etching the layers, the curable resin mask defining the grade and adapted to resist etching.

CROSS REFERENCE TO RELATED APPLICATIONS

The following commonly assigned U.S. patent applications are related andare all incorporated by reference in their entirety: “High-EnergyCapacitors for Implantable Defibrillators,” U.S. Pat. No. 6,556,863;“Method and Apparatus for Single High Voltage Aluminum CapacitorDesign,” Ser. No. 60/588,905, filed on Jul. 16, 2004 (Attorney DocketNo. 279.709PRV); “Method for Interconnection Anodes and Cathodes in aFlat Capacitor,” Ser. No. 10/874,798, filed on Jun. 23, 2004 (AttorneyDocket No. 279.823US1).

FIELD OF THE INVENTION

This disclosure relates generally to electrolytic capacitors, and moreparticularly, to capacitors with electrodes partially covered withdielectric.

BACKGROUND

As technology progresses, the sizes of electrical interconnectionsbecome smaller. Concurrent and related to these size reductions,electronic components are becoming more compact, occupying new, smallershapes. Electronic components of reduced size, having new shapes,require new methods and structures.

One electronic component having electrical interconnections is thecapacitor. To promote size reductions, new shapes, and robustmanufacturing, new electrical connections for capacitors are needed.These new interconnections should not damage capacitors or theirsubcomponents.

SUMMARY

The above-mentioned problems and others not expressly discussed hereinare addressed by the present subject matter and will be understood byreading and studying this specification.

The present subject matter includes the process of depositing a curableresin mask onto a foil and curing the curable resin mask onto the foil.Additionally, the process includes etching the foil while the curableresin mask restricts the etchant. The process includes removing thecured mask from the foil. The process additionally includes anodizingthe foil. Also, the process includes assembling the shapes into a flatstack, and inserting the flat stack into a capacitor case.

Additionally, the present subject matter includes a case with a firstaperture sized for passage of the capacitor stack and a feedthroughhole, and a capacitor stack disposed in the case, the capacitor stackincluding one or more substantially planar electrode layers, the one ormore substantially planar electrode layers having an etched surface, anunetched surface, and a grade bordering the etched surface and theunetched surface. Also, the present subject matter includes a lidconforming to the first aperture and sealingly connected to the materialdefining the first aperture, and a feedthrough assembly connected to thecapacitor stack and passing through the feedthrough hole and sealinglyconnected to the material defining the feedthrough hole. Additionally,electrolyte is disposed in the case. In the present subject matter, theone or more substantially planar electrode layers are made by printing acurable resin mask onto the one or more substantially planar electrodelayers and etching the layers, the curable resin mask defining the gradeand adapted to resist etching.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects will be apparent to persons skilled in the art upon reading andunderstanding the following detailed description and viewing thedrawings that form a part thereof, each of which are not to be taken ina limiting sense. The scope of the present invention is defined by theappended claims and their legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a flat capacitor according to oneembodiment of the present subject matter.

FIG. 2 is an exploded isometric view of portions of the capacitor ofFIG. 1.

FIG. 3 is a top view of a connection member-to-foil connection and afoil-to-foil connection according to one or more embodiments of thepresent subject matter.

FIG. 4 is a side view of a staking machine having a staking tool forperforming staking according to one embodiment of the present subjectmatter.

FIG. 5 is an isometric view of the staking tool of FIG. 4.

FIG. 6 is a enlarged side view of the staking tool of FIG. 5.

FIG. 7 is an enlarged side view of the staking machine of FIG. 4.

FIG. 8 is a flowchart depicting a method for performing connectionmember-to-foil staking according to one embodiment of the presentsubject matter.

FIG. 9A is a cross-sectional side view of portions of the capacitorstack of FIG. 3.

FIG. 9B is a cross-sectional side view of portions of the capacitorstack of FIG.3.

FIG. 10 is an isometric view of a staking tool for performingfoil-to-foil staking according to one embodiment of the present subjectmatter.

FIG. 11 is a flowchart of a method for performing foil-to-foil stakingaccording to one embodiment of the present subject matter.

FIG. 12 is a cross-sectional isometric view of a capacitor havingedge-connected connection members according to one embodiment of thepresent subject matter.

FIG. 13 is a cross-sectional isometric view of a capacitor havingedge-connected connection members according to another embodiment of thepresent subject matter.

FIG. 14 is a cross-sectional isometric view of a capacitor havingedge-connected connection members according to another embodiment of thepresent subject matter.

FIG. 15 is a cross-sectional isometric view of a capacitor havingedge-connected connection members according to another embodiment of thepresent subject matter.

FIG. 16 is an perspective view of an anode foil according to oneembodiment of the present subject matter.

FIGS. 17A-B show flowcharts depicting methods of preparing anode foils,according to various embodiments of the present subject matter.

FIG. 18 is a perspective view of a flat capacitor according to oneembodiment of the present subject matter.

FIG. 19 is an exploded perspective view of a capacitor stack constructedin accordance with one embodiment.

FIG. 20 is an exploded perspective view of an anode stack constructed inaccordance with one embodiment.

FIG. 21 is a side view of an anode stack and edge connection memberconstructed in accordance with one embodiment.

FIG. 22 is a side view of a separator constructed in accordance with oneembodiment;

FIG. 23 is an exploded perspective view of a cathode base layer stackconstructed in accordance with one embodiment.

FIG. 24 is an exploded perspective view of a cathode stack constructedin accordance with one embodiment.

FIG. 25 is an exploded perspective view of a cathode stack constructedin accordance with one embodiment.

FIG. 26 is an exploded perspective view of a cathode stack constructedin accordance with one embodiment.

FIG. 27 is an exploded perspective view of a cathode stack constructedin accordance with one embodiment.

FIG. 28A is a perspective view of an alignment mechanism constructed inaccordance with one embodiment.

FIG. 28B is a perspective view of an alignment mechanism constructed inaccordance with one embodiment.

FIG. 29 is a perspective view of a capacitor stack in an alignmentmechanism constructed in accordance with one embodiment.

FIG. 30 is a top view of an anode stack aligned within an externalalignment mechanism constructed in accordance with one embodiment.

FIG. 31 is a top view of staking locations for a plurality of anodestacks constructed in accordance with one embodiment.

FIG. 32 is a cross-sectional view of the staking locations of FIG. 31.

FIG. 33 is a top view of a cathode stack within an alignment mechanismconstructed in accordance with one embodiment.

FIG. 34 is a perspective view of a cathode stack in an alignmentmechanism constructed in accordance with one embodiment.

FIG. 35 is a top view of a capacitor stack according to one embodiment.

FIG. 36 is a side schematic view of the capacitor stack of FIG. 35.

FIG. 37 is a side schematic view of a capacitor stack according to oneembodiment.

FIG. 38 is a cross-sectional view of a capacitor stack constructed inaccordance with one embodiment.

FIG. 39 is an exploded view of an anode stack constructed in accordancewith one embodiment.

FIG. 40 is an exploded view of a modified anode stack constructed inaccordance with one embodiment.

FIG. 41 is an exploded view of a mixed anode stack constructed inaccordance with one embodiment.

FIG. 42 is a cross-sectional view of a capacitor stack constructed inaccordance with one embodiment.

FIG. 43 is a perspective view of a capacitor stack according to oneembodiment.

FIG. 44 is a perspective view of the capacitor stack of FIG. 43.

FIG. 45 is a perspective view of the capacitor stack of FIG. 43 with aplurality of tab groups positioned on the top surface of the capacitorstack.

FIG. 46 is a partial exploded side view of the capacitor stack of FIG.43.

FIG. 47 is a partial side view of a capacitor stack according to oneembodiment.

FIG. 48 is a flow chart of a method for manufacturing a capacitor inaccordance with one embodiment.

FIG. 49 is a partial cross-sectional view of a capacitor havingcapacitor modules with edges staggered in a first dimension to define acurved profile;

FIG. 50 is a partial cross-sectional view of a capacitor showing thatits capacitor modules are staggered in a second dimension to defineanother curved profile;

FIG. 51 is a partial cross-sectional view of an implantable heartmonitor including a monitor housing and two capacitors having curvedprofiles that abut interior curved portions of the monitor housing.

FIG. 52 is a perspective view of a capacitor-battery assembly includingtwo stacked U-shaped capacitors and a battery nested within thecapacitors.

FIG. 53 is a front view of the FIG. 52 assembly without the battery.

FIG. 54 is a side view of the FIG. 52 assembly.

FIG. 55 is a top view of the FIG. 52 assembly.

FIG. 56 is an isometric cross-section view of portions of a capacitorstack according to one embodiment.

FIG. 57 is a top view of a cathode structure according to oneembodiment.

FIG. 58 is an isometric view of a flat capacitor in accord with oneembodiment of the present subject matter.

FIG. 59 is an exploded isometric view of the flat capacitor of FIG. 58.

FIG. 60 is another exploded isometric view of the flat capacitor of FIG.58.

FIG. 61 is a cross-sectional view of the feedthrough assembly of FIG.58.

FIG. 62A is an isometric view of the exemplary feedthrough assembly ofFIG. 58.

FIG. 62B is a side view of the exemplary feedthrough assembly of FIG.58.

FIG. 63 is an isometric view of an exemplary coupling member in accordwith one embodiment of the present subject matter.

FIG. 64 is an isometric view of another exemplary coupling member inaccord with one embodiment of the present subject matter.

FIG. 65A is an isometric view of another exemplary coupling member inaccord with one embodiment of the present subject matter.

FIG. 65B is an isometric view of another exemplary coupling member inaccord with one embodiment of the present subject matter.

FIG. 66 is a side view of the feedthrough assembly of FIG. 58.

FIG. 67 is an exploded isometric view of a flat capacitor according toone embodiment of the present subject matter.

FIG. 68 is a cross-sectional view of the feedthrough assembly of FIG.67.

FIG. 69 is a cross-sectional side view showing a feedthrough plugaccording to one embodiment.

FIG. 70 is an exploded view of a flat capacitor according to oneembodiment of the present subject matter.

FIG. 71 is an isometric view of the feedthrough assembly of FIG. 70.

FIG. 72 is a cross-section view of the feedthrough assembly of FIG. 70.

FIG. 73 is a cross-section view of another exemplary feedthroughassembly according to one embodiment of the present subject matter.

FIG. 74 is a cross-section view of another exemplary feedthroughassembly according to one embodiment of the present subject matter.

FIG. 75 is a flow-chart of a method for manufacturing an electrolyticcapacitor according to one embodiment of the present subject matter.

FIG. 76 is a flow-chart of a method for replacing a first capacitor witha second capacitor according to one embodiment of the present subjectmatter.

FIG. 77 is a flow-chart of a method for manufacturing an implantabledefibrillator according to one embodiment of the present subject matter.

FIG. 78 is an exploded perspective view of a capacitor according to oneembodiment of the present subject matter.

FIG. 79 is a cross sectional view of portions of the capacitive stack ofFIG. 78.

FIG. 80 is a partial cross sectional view of a capacitor with a cathodeconductor positioned between the cover and the case according to oneembodiment.

FIG. 81 is a partial cross sectional view of a capacitor with thecathode conductor attached to the cover and the case according to oneembodiment.

FIG. 82 is a partial cross sectional view of a capacitor with thecathode conductor welded to the cover and the case according to oneembodiment.

FIG. 83A is a view of a flat capacitor foil with an attached round wireconnector according to one embodiment.

FIG. 83B is a perspective view of a flat capacitor showing round wireconnectors for interconnecting anode and cathode plates.

FIG. 84 is a view of a capacitor with an expanded end of a terminal wireattached to a case according to one embodiment.

FIG. 85A is a view of a terminal wire attached to a case according toone embodiment.

FIG. 85B is a view of a terminal wire attached to a case according toone embodiment.

FIG. 86 is an exploded perspective view illustrating a capacitor asconstructed in accordance with one embodiment.

FIG. 87 is an exploded perspective view illustrating a capacitor stackas constructed in accordance with one embodiment.

FIG. 88 is an exploded perspective view illustrating an anode stack asconstructed in accordance with one embodiment.

FIG. 89 is an exploded perspective view illustrating a cathode baselayer as constructed in accordance with one embodiment.

FIG. 90 is a cross-sectional view illustrating a portion of a capacitoras constructed in accordance with one embodiment.

FIG. 91 is an exploded perspective view illustrating a capacitor stackas constructed in accordance with one embodiment.

FIG. 92 is an exploded perspective view illustrating a cathode stack asconstructed in accordance with another embodiment.

FIG. 93 is a cross-sectional view taken along 8-8 of FIG. 94illustrating a portion of a capacitor as constructed in accordance withone embodiment.

FIG. 94 is a top plan view illustrating a capacitor as constructed inaccordance with another embodiment.

FIG. 95 is a top plan view illustrating an anode as constructed inaccordance with one embodiment.

FIG. 96 is a perspective view illustrating a capacitor stack asconstructed in accordance with one embodiment.

FIG. 97 is a perspective view illustrating a capacitor stack asconstructed in accordance with one embodiment.

FIG. 98 is a perspective view illustrating a capacitor stack asconstructed in accordance with one embodiment.

FIG. 99 is a cross-sectional view illustrating a portion of a capacitoras constructed in accordance with one embodiment.

FIG. 100 is a cross-sectional view taken along 15-15 of FIG. 94illustrating a portion of a capacitor as constructed in accordance withone embodiment.

FIG. 101A is a top view of an anode foil for use in constructing acapacitor according to one embodiment of the present subject matter.

FIG. 101B is a top view of a cathode foil for use in constructing acapacitor according to one embodiment of the present subject matter.

FIG. 102A is a top view of an anode foil for use in constructing acapacitor according to one embodiment of the present subject matter.

FIG. 102B is a top view of a cathode foil for use in constructing acapacitor according to one embodiment of the present subject matter.

FIG. 103 is a perspective view of a stack of one or more anodes andcathodes of FIGS. 101A and 2B.

FIG. 104A is a perspective view of the stack of FIG. 103 after the stackhas been processed according to one embodiment of the present subjectmatter.

FIG. 104B is a perspective view of a stack of anodes and cathodesaccording to one embodiment.

FIG. 104C is a perspective view of the stack of FIG. 5B after the stackhas been processed according to one embodiment of the present invention.

FIG. 105 is a flowchart depicting a method of interconnecting anodes andcathode foils of a capacitor according to one embodiment of the presentsubject matter.

FIG. 106A shows a top view of a capacitor stack according to oneembodiment.

FIG. 106B shows a cross-section of a portion of FIG. 106A.

FIG. 106C shows a partially etched anode foil according to oneembodiment.

FIG. 106D shows a side view of a foil having masks according to oneembodiment.

FIG. 106E show a top view of FIG. 106D.

FIG. 106F shows a method according to one embodiment.

FIG. 107A is a schematic of a capacitor having a dual-compartment case.

FIG. 107B is a schematic of a capacitor having a dual-compartment casethat also serves as a conductor.

FIG. 108 is a schematic of a capacitor having a three compartment case.

FIG. 109 is a perspective view of a flat capacitor including apressure-relief mechanism according to one embodiment of the presentsubject matter.

FIG. 110 is a perspective view of a cylindrical electrolytic capacitorincluding a pressure-relief mechanism according to one embodiment of thepresent subject matter.

FIG. 111 is a cross-sectional view of a pressure-relief device in accordwith one embodiment.

FIG. 112 is a cross-sectional view of a pressure-relief device in accordwith one embodiment.

FIG. 113 is a cross-sectional view of a pressure-relief device in accordwith one embodiment.

FIG. 114 is a cross-sectional view of a pressure-relief device in accordwith one embodiment.

FIG. 115 is a schematic representation of an implantable medical deviceaccording to one embodiment of the present subject matter.

FIGS. 116A-116C illustrate a graph representing characteristics of anelectrode, according to various embodiments of the present subjectmatter.

FIG. 117 illustrates one example of a mask applied to the electrode,according to various embodiments of the present subject matter.

FIGS. 118A-118F illustrate varying designs of a mask applied to theelectrode, according to various embodiments of the present subjectmatter.

FIG. 119 shows a process for making a foil with a partially etched area,according to various embodiments of the present subject matter.

FIG. 120 shows a flat capacitor according to one embodiment of thepresent subject matter.

FIG. 121 illustrates a close up view of the plate and plug of FIG. 1,according to one embodiment of the present subject matter.

FIG. 122 illustrates an exploded view of a capacitor, according to oneembodiment of the present subject matter.

FIG. 123A illustrates the front view of a plate, according to oneembodiment of the present subject matter.

FIG. 123B illustrates a cross section of a side view of a plate,according to one embodiment of the present subject matter.

FIG. 124 shows a side view of conductor attached to a plate with a firstmajor face, according to one embodiment of the present subject matter.

FIG. 125 shows a cross-sectional side view of details of one embodimentof feedthrough assembly.

FIG. 126 shows a method for manufacturing an implantable defibrillatoraccording to one embodiment of the present subject matter.

FIG. 127 shows a method for manufacturing an implantable defibrillatoraccording to one embodiment of the present subject matter.

FIG. 128 shows a method for manufacturing an implantable defibrillatoraccording to one embodiment of the present subject matter.

DETAILED DESCRIPTION

The following detailed description of the present invention refers tosubject matter in the accompanying drawings which show, by way ofillustration, specific aspects and embodiments in which the presentsubject matter may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thepresent subject matter. It will be apparent, however, to one skilled inthe art that the various embodiments may be practiced without some ofthese specific details. References to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.The following detailed description is, therefore, not to be taken in alimiting sense, and the scope is defined only by the appended claims,along with the full scope of legal equivalents to which such claims areentitled.

FIG. 1 shows a flat capacitor 100 according to one embodiment of thepresent subject matter. Although capacitor 100 is a D-shaped capacitor,in other embodiments, the capacitor is other desirable shapes,including, but not limited to rectangular, circular, oval, square, orother symmetrical or asymmetrical shape. Capacitor 100 includes a case101 which contains a capacitor stack 102. In one embodiment, case 101 ismanufactured from a conductive material, such as aluminum. In otherembodiments, the case is manufactured using a nonconductive material,such as a ceramic or a plastic. One example uses a case 101 which isformed from aluminum which is from about 0.010 inches thick to about0.012 inches thick. In some examples, the case is electrically connectedto an electrode of the capacitor, and one example uses the case as partof the cathode. For example, a conductive material is attached to thecathode and to the case, internal to the housing 101, in variousembodiments.

Capacitor 100 includes a first terminal 103 and a second terminal 104for connecting capacitor stack 102 to an outside electrical component,such as implantable medical device circuitry. In one embodiment,terminal 103 is a feedthrough terminal insulated from case 101, whileterminal 104 is directly connected to case 101. Alternatively, thecapacitor incorporates other connection methods. For instance, in someembodiments, capacitor 100 includes two feedthrough terminals.

In the present embodiment, capacitor stack 102 includes capacitormodules or elements 105 a, 105 b, 105 c, . . . , 105 n.

FIG. 2 shows details of one example of capacitor element 105 a, which isrepresentative of capacitor elements 105 b-105 n. Element 105 a includesa cathode 201, a separator 202, and an anode stack 203. In otherembodiments, other numbers and arrangements of anodes, cathodes, andseparators are utilized.

Cathode 201 is a foil attached to other cathodes of capacitor stack 102and to terminal 104. In some embodiments, cathode 201 can includealuminum, tantalum, hafnium, niobium, titanium, zirconium, andcombinations of these metals. In one embodiment, cathode 201 isconstructed by taking an aluminum (98% purity or higher) base metal andcoating it with titanium oxide, titanium nitride, or titanium pentoxideusing sputtering, plating, vacuum deposition, or other coatingtechniques. In some embodiments, titanium itself is used with asubsequent processing step used to oxidize the titanium resulting inTi0, Ti0₂, TiN, Ti₂0₅, or other high dielectric constant oxide.

The resulting titanium-coated cathode material has a higher capacitanceper unit area than traditional aluminum electrolytic capacitor cathodes.Traditional cathodes which are 98% aluminum purity or higher generallyhave capacitance per unit area of approximately 250 uF/cm² for 30 micronthick foil, with an oxide breakdown voltage in the 1-3 volt range.However, a cathode as described above results in a capacitance per unitarea which, in some embodiments, is as high as 1000 uF/cm² or more.

Advantageously, this provides a single cathode which services severallayers of anodic foil without exceeding the oxide breakdown voltage.When using a traditional cathode to service several layers (2 or more)of anodic foil, the cathode voltage may rise as high as 5 or more volts,which is usually greater than the breakdown voltage. When this occurs,the aluminum cathode begins to form oxide by a hydration process whichextracts oxygen from the water present in the electrolyte. The reactionproduces hydrogen as a byproduct which in turn has the effect ofcreating an internal pressure within the capacitor causing anundesirable mechanical bulge in the layers from the capacitor stack, orin the case. Therefore, the titanium-coated cathode described aboveserves as a corrective mechanism for hydrogen generation.

Separator 202 is located between each anode stack 203 and cathode 201.In one embodiment, separator 202 consists of two sheets of 0.0005 inchesthick kraft paper impregnated with an electrolyte. In some embodiments,separator 202 includes a single sheet or three or more sheets.

The electrolyte can be any suitable electrolyte for an electrolyticcapacitor, such as an ethylene-glycol base combined with polyphosphates,ammonium pentaborate, and/or an adipic acid solute. In one embodiment,the electrolyte includes butyrolactone and ethylene glycol, such asB103AD electrolyte manufactured by Boundary Technologies, Inc. ofNorthbrook, Ill. 60065 USA.

In one embodiment, each anode stack 203 is a multi-anode stack includingthree anode foils 203 a, 203 b, and 203 c. In other embodiments, anodestack 203 includes one, two, three or more anode foils having a varietyof anode shapes. Each anode foil has a major surface 206 and an edgeface 207 generally perpendicular to major surface 206. Anodes 203 a, 203b, and 203 c are generally foil structures and can include aluminum,tantalum, hafnium, niobium, titanium, zirconium, and combinations ofthese metals.

In one embodiment, anode foils 203 a-203 c are high formation voltageanode foils, which will be discussed below. In other embodiments, theanode foils are medium and/or low formation voltage foils. In oneembodiment, the major surface of each anode foil 203 a-203 c isroughened or etched to increase its microscopic surface area. Thisincreases the microscopic surface area of the foil with no increase involume. Other embodiments use tunnel-etched, core-etched, and/orperforated-core-etched foil structures. Other embodiments utilize otherfoil compositions and classes of foil compositions.

Depending on which process is used to construct the anode, varioussurfaces are coated with a dielectric. For example, in embodiments wherethe anode shapes are punched from a larger sheet which has previouslybeen coated with dielectric, only the surfaces which have not beensheared in the punching process are coated with dielectric. But if thedielectric is formed after punching, in various embodiments, allsurfaces are coated. In some embodiments, anodes are punched from alarger sheet to minimize handling defects due to handling during themanufacturing process. For example, if a larger sheet is used as amaterial from which a number of anode layers are punched, machines oroperators can grasp the material which is not intended to form the finalanode. Generally, in embodiments where the entire anode is not coveredwith dielectric, the anode must be aged.

Attachable to anode stack 203 at major surface 206 of anode 203 b is afoil connection structure such as a tab or connection member 204, madefrom aluminum, which electrically connects each anode foil to the otheranodes of the capacitor. For instance, in the present embodiment, eachtab or connection member 204 of each capacitor element 105 a, . . . ,105 n is connected to each other connection member 204 and coupled toterminal 103 for electrically coupling the anode to a component orelectronic assembly outside the case. In one embodiment, each anode 203a includes a notch 205 which is slightly larger than the width ofconnection member 204.

Connection member 204 fits within notch 205, and this preventsconnection member 204 from causing a bulge in anode stack 203. However,other embodiments omit the notch to avoid reducing the surface area ofanode 203 a. In other embodiments, connection member 204 is omitted andan integrally connected tab connection member is utilized for one ormore anode foils.

FIG. 3 shows a top view of capacitor element 105 a. In one embodiment,each anode foil 203 a-203 c of multi-anode stack 203 is interconnectedto the other foils 203 a-203 c of multi-anode stack 203 at a stake weldjoint 302 a, which will be discussed in more detail below.

In one embodiment, connection member 204 is attached to major surface206 of anode 203 b. Member 204 is attached to anode 203 b by a methodthe inventors call micro-staking. Micro-staking is a cold welding orstaking process which uses a small staking point. In one embodiment,each micro-stake joint 301 a and 301 b is approximately 0.015″ (0.381mm) in diameter. In other embodiments, micro-stake joints 301 a and 301b are less than or equal to approximately 0.030″ (0.762 mm) in diameter.In some embodiments, joints 301 a and 301 b can range from approximately0.005″ (0.127 mm) to approximately 0.030″ (0.762 mm). In someembodiments, joints 301 a and 301 b can range from approximately 0.010″(0.254 mm) to approximately 0.020″ (0.508 mm).

The small size of joints 301 a and 301 b allows one to use smallerconnection members 204 and to place them closer to an edge 303 of anode203 b than typical capacitors. For instance, in one embodiment, joints301 a and 301 b are approximately 0.120″ (3.048 mm) from edge 303, andjoint 301 a is approximately 0.100″ (2.54 mm) away from the top edge offoil 206. This in turn allows notch 205 to be smaller than in typicalcapacitors. For instance, in one embodiment, notch 205 is approximately0.200″ by 0.200″ (5.08 mm by 5.08 mm). A smaller notch allows moresurface area for anode 203 a and thus more capacitance per unit volume.The small size of joints 301 a and 301 b also allows use of a morehighly etched, and hence more brittle, foil since making the small weldjoint is less likely to crack the brittle foil than large weld joints.

In one embodiment, member 204 is attached to anode 203 b at twomicro-stake joints, 301 a and 301 b. Some embodiments only have a singlemicro-stake joint 301 and others have three or more micro-stake joints.However, the two welds of this embodiment allow for a redundant weld incase either of the welds fail. In other embodiments, tab 204 is attachedby other techniques, such as laser welding or soldering. In oneembodiment, tab 204 is attached only to a single anode foil, anode 203b.

FIG. 4 shows a staking machine 400 for making micro-stake joints 301 aand 301 b according to one embodiment. Machine 400 includes a hardened,planar, anvil surface 402 and a handle 403. A micro-staking tool 401 isshown installed in machine 400. In one embodiment, machine 400 is ahand-operated press manufactured by Gechter Co. of Germany.Alternatively, by way of example, but not limitation, other cold-weldingmachines, pneumatic presses, electronic solenoid, electro-punch, airover hydraulic, or hydraulic presses can be used to perform themicro-staking process.

Tool 401 is held within a tool holder or collet 404 which is operativelycoupled to handle 403. Pulling handle 403 moves collet 404 and tool 401towards surface 402. Alternatively, as noted above, pneumatic pressure,an electric driver, hydraulic, solenoid, or other actuation means can beused to activate tool 401.

FIGS. 5 and 6 show details of micro-staking tool 401 for performingconnection member-to-foil staking according to one embodiment of thepresent subject matter. Tool 401 is machined from a stainless steel or atool steel. Tool 401 includes a first end 502 for mounting to collet 404and a second end 504 for making the micro-staked joints. End 504includes a first staking pin 505 and a second staking pin 506. In oneembodiment, pins 505 and 506 are approximately 0.040″ (1.016 mm) apart.In some embodiments, a single pin 505 is used for making a single weldjoint.

In one embodiment, each pin 505 and 506 has a generally frustoconicalshape rising at an angle a of approximately 30°. Each pin has a circularcross-section having a diameter of approximately 0.028″ (0.7112 mm) atits base 601 and a diameter of approximately 0.015″ (0.381 mm) at itstip 602. Alternatively, tip 602 can range in diameter from approximately0.005″ (0.127 mm) to approximately 0.030″ (0.762 mm); some embodimentsrange from approximately 0.010″ (0.254 mm) to approximately 0.030″(0.762 mm); other embodiments range from equal to or greater thanapproximately 0.030″ (0.762 mm) in diameter. In other embodiments, tip602 is less than or equal to approximately 0.030″ (0.762 mm) indiameter. In some embodiments, tip 602 ranges from approximately 0.010″(0.254 mm) to approximately 0.020″ (0.508 mm). By way of example, thepin can have an oval, diamond, elliptical, rectangular, square, or othershaped cross-section. In one embodiment, the tip of each pin 505 and 506is flat. However, in other embodiments, tips are domed, concave, convex,rounded, or indented and may include a plurality of angles.

FIG. 7 shows a close-up view of one embodiment of tool 401 being used tomicro-stake connection member 204 to anode 203 b. In one embodiment,connection member 204 rests against hardened surface 402 and anode 203 blies between connection member 204 and tool 401. Such an arrangement(wherein the connection member rests against the hardened surface andthe anode foil is above it) of connection members and foils decreasesthe likelihood of cracking the brittle foil of anode 203 b duringmicro-staking.

In one embodiment, the hand-operated staking machine is set so thatthere is a distance 401 t of approximately 0.001″ (0.0254 mm) betweenanvil surface 402 and tool 401 when the tool is in its lowest orterminal position 401′. To micro-stake connection member 204 to anode203 b, tool 401 is driven first into anode 203 b, which is compressedinto connection member 204. In one embodiment, tool 401 is driven to adisplacement of 0.001″ (0.0254 mm) when micro-staking. In otherembodiments, where air, hydraulic, or solenoid force is used, tool 401is driven under a force in the range of 100 to 1000 pounds until thetool bottoms out. In those embodiments, there is no set clearance.

FIG. 8 shows a flowchart of one example of a method 600 of joining aconnection member and a foil together. Method 600 includes processblocks 610-630. Block 610 entails setting a staking tool; block 620entails stacking the connection member and the foil; and block 630entails forcing the foil and connection member together. In oneembodiment, a staking machine such as machine 400 having hardenedsurface 402, and a staking tool such as tool 401 having at least onestaking pin 505, are used to perform the method.

Block 610 includes setting staking pin 505 so that there is anapproximately 0.001″ (0.0254 mm) clearance or displacement between anvilsurface 402 and pin 505 when the tool is in its lowest or terminalposition. Typically this is done when machine 400 is a hand-operatedpress. In some embodiments, block 610 is omitted. For instance, as notedabove, pneumatic, hydraulic, air over hydraulic, electric solenoid,electric driver, or other actuation means can be used to activate tool401. In these embodiments, tool 401 is set to be driven under a force ofapproximately 100 pounds to 1000 pounds until it bottoms out or until apredetermined displacement is reached.

Block 620 includes placing a connection member, for instance connectionmember 204, on hardened surface 402 and stacking or placing a foil, suchas foil 203 b, on top of connection member 204.

In block 630, the staking machine is activated so that tool 401 drivesdownward and forces the foil and the connection member together betweenhardened surface 402 and staking pin 505.

The micro-staking process results in the micro-staked weld joints 301 aand 301 b as shown in FIG. 3. As described above, in one embodiment,these welds are relatively close to edge 303 of the anode. Thus, arelatively small connection member can be used and a relatively smallnotch can be used in the notched anode, such as anode 203 a. Thisincreases the capacitive surface area of the anode without increasingthe volume of the capacitor itself, thus increasing its energy density.

Referring again to FIG. 3, each anode foil 203 a-203 c of multi-anodestack 203 is interconnected to the other foils 203 a-203 c ofmulti-anode stack 203 at a stake weld joint 302 a. In one embodiment,foil-to-foil joint 302 a has a diameter 302 d of approximately 0.025″(0.635 mm). In some embodiments, joint diameter 302 d is less thanapproximately 0.060″ (1.524 mm). In various embodiments, joint diameter302 d ranges from approximately 0.015″ (0.381 mm) to less thanapproximately 0.060″ (1.524 mm).

FIG. 9A shows a cross-sectional view of the foil connection of anodestack 203. Foils 203 a-203 c are connected by foil-to-foil weld 302 aand tab 204 is attached to anode 203 b by weld 301 b. In variousembodiments, foils 203 a-203 c are different types of etched foils. Forexample, in one embodiment, all three foils 203 a-203 c aretunnel-etched foils. In another embodiment, at least one of the foils,for example, foil 203 b is a core-etched foil or a perforatedcore-etched foil. Other embodiments present other permutations of foils.The present joining method is able to successfully join variouspermutation of materials, thus permitting capacitor manufacturers todesign the capacitor with fewer material limitations.

FIG. 9B shows a cross-sectional view of portions of capacitor stack 102.In the portion shown, capacitor stack 102 includes anode stacks 203a-203 c. Between each anode stack is separator 202 and cathode 201. Eachanode stack is joined by respective stake welds 302 a-302 c. In theexemplary capacitor stack, each stake weld 302 a-302 c of each anodestack 203 a-203 c is in a different location relative to the majorsurface of each anode stack. This staggered arrangement of weldsprovides that the bulges created at any single weld 302 a-302 c do notcumulate along any single point or vertical line in the capacitor stack.This staggered arrangement helps reduce the overall thickness ofcapacitor stack 102.

FIG. 10 shows a staking tool 701 for staking foils 203 a-203 c togetheraccording to one embodiment of the present subject matter. In oneembodiment, a staking machine such as described in FIG. 4 is used.Alternatively, other cold welding machines, pneumatic presses,hydraulic, air over hydraulic or electric solenoid machines are used toperform the staking process.

In some embodiments, such as when the staking machine is hand-operated,tool 701 is driven to a displacement of 0.001″ (0.0254 mm) from thehardened surface of the staking machine when the staking is being done.In some embodiments, such as when pneumatic, hydraulic, air overhydraulic or electric solenoid presses are used, tool 701 is drivenunder a force of approximately 100 pounds to 1000 pounds until itbottoms out or until a predetermined displacement is reached.

In one embodiment, tool 701 is machined from a stainless steel or a toolsteel. Tool 701 includes a first end 702 for mounting to a collet in astaking machine and a second end 704 for making the foil-to-foil stakedjoints. End 704 includes a stake pin 705 having a tip 706.

In one embodiment, pin 705 has a generally frusto-conical shape risingat an angle α of approximately 30°. The example pin has a circularcross-section. Pin 705 can also have an oval, diamond, elliptical,rectangular, or square shaped cross-section. Pin 705 has a diameter ofapproximately 0.025″ (0.635 mm) at tip 706. Alternatively, in someembodiments, tip 706 is less than approximately 0.060″ (1.524 mm). Invarious embodiments, tip 706 ranges from approximately 0.015″ (0.381 mm)to less than approximately 0.060″ (1.524 mm). In one embodiment, the tipof pin 705 has a flat surface. However, in other embodiments, the tip isdomed, convex, concave, rounded, or may have a plurality of angles.

FIG. 11 shows a flowchart of one example of a method 700 of assemblingtwo or more anode foils, such as anodes 203 a-203 c. In one method,three anodes are joined. In other embodiments two, three, four, or morefoils are joined using the method. In some embodiments, method 700 joinsa stack of foils which includes one or more core-etched foils. However,in various other embodiments, method 700 joins a stack comprising onlytunnel-etched foils.

Method 700 includes process blocks 710-730. Block 710 entails setting astaking tool; block 720 entails stacking foils; and block 730 entailsforcing the foils together. In one embodiment, a staking machine such asmachine 400 having hardened surface 402, and a staking tool such as tool701 having staking pin 705 are used to perform the method.

Block 710 includes setting staking pin 705 so that there is anapproximately 0.001″ (0.0254 mm) clearance or displacement betweenhardened surface 402 and pin 705 when the tool is in its lowest orterminal position. Typically this is done when the staking machine is ahand-operated press.

In some embodiments, block 710 is omitted. For instance, as noted above,pneumatic, hydraulic, air over hydraulic, electric solenoid, electricdriver, or other actuation means can be used to activate tool 701. Inthese embodiments, tool 701 is set to be driven under a force ofapproximately 100 pounds to 1000 pounds until it bottoms out or until apredetermined displacement is reached.

Block 720 includes placing a first foil, for instance foil 203 c, onhardened surface 402 and stacking or placing one or more foils, such asfoils 203 b and 203 a, on top of foil 203 c so that the major surfacesof adjacent foils are in contact with each other and the foils arestacked in a dimension perpendicular to a major surface of each of thefoils. After block 720, foil stack 203 is positioned between hardenedsurface 402 and staking tool 701. In some embodiments, two, three, fouror more foils are stacked on the hardened surface.

In block 730, the staking machine is activated so that tool 701 drivesdownward and forces the anode foils between hardened surface 402 andstaking pin 705. In one method, the tool is driven until a displacementof 0.001″ (0.0254 mm) between hardened surface 402 and pin 705 isreached. Alternatively, as noted above, if pneumatic, hydraulic, airover hydraulic, electric solenoid, electric driver, or other actuationmeans are used to activate tool 701, the tool is set to be driven undera force of approximately 100 pounds to 1000 pounds until it bottoms outor until a pre-determined displacement is reached. One embodiment ofstaking method 700 results in the weld joint 302 a as shown in FIG. 3.

Among other advantages of the present method, since joint 302 a issmall, a more brittle foil can be used and this increases the capacitivesurface area of the anode without increasing the volume of the capacitoritself, thus increasing its energy density. Also, a wide variety of foiltypes can be staked together.

In one embodiment, tab or connection member 204 is staked ormicro-staked to anode 203 b before the foils 203 a-203 c are stakedtogether by method 700. Attaching the connection member to only one foildecreases the chance of the highly etched and brittle foil crackingunder the stress of the weld. This allows use of foils with greaterdegrees of etching and thus, smaller volume capacitors.

In assembling capacitor 100, one example method includes assembling twoor more anode stacks 203 by method 700. In one embodiment, each anodestack of capacitor 100 has a respective weld 302 a-302 c in a differentlocation relative to the major surface of the anode stacks. The two ormore anode stacks are assembled into capacitor elements 105 a-105 n.Each anode tab 204 of each element 105 a-105 n is connected to eachadjacent anode tab 204. In one embodiment, the connection members 204are connected to each other by a method called edge-welding. In otherembodiments, the tabs are connected by staking, laser welding,ultrasonic welding, or other methods.

FIG. 12 shows a connection member-to-connection member connectionaccording to one embodiment of the present subject matter. In thepartial view shown, each capacitor element 105 a-105 d has a respectivetab or connection member 204 a-204 d attached to it by an attachmentmethod. In one embodiment, micro-staking is used to connect theconnection members. In one embodiment, each connection member 204 a-204d is approximately 0.004″ (0.1016 mm) thick to fill the notch of anodefoil 203 a, which is 0.004″ (0.1016 mm) thick. In other embodiments, theanode foil and the cathode and paper assembly have different thicknessesand so does the connection member. In some embodiments, anode 203 a isnot notched and each connection member 204 a-204 d is sandwiched betweena pair of foils.

Each connection member 204 a-204 d is positioned so that an exposedfront end face 810 of each connection member is flush with the exposedfront end faces of its neighboring connection members, forming a flatfrontal surface area. In some embodiments, the end faces 810 are cut tobe flush with each other. The exposed face or surface of each connectionmember is the surface or face of the connection member that is open orrevealed on the outside of capacitor stack 102.

Each connection member 204 a-204 d is connected to its neighboringconnection members along their respective front faces 810. Threedifferent embodiments of edge connections 801 are shown. Connections 801include a laser seam edge-weld 801 a, a wire bonded connection 801 b,and a laser cross-wise edge-weld 801 c. However, in the presentembodiment only one need be used at any given time. In one embodiment(not shown), edge connection 801 is provided by an ultrasonic edge weld.

In one embodiment, laser edge-weld 801 a is provided by a Lumonics JK702Nd-YAG laser welder using settings of approximately 1.4 Joules at afrequency of 100 hertz. The laser power is approximately 110 Watts, thepulse height is approximately 22%, and the pulse width is approximately1.4 msec. In various embodiments, the pulse width ranges from about 1.0ms to about 2.5 ms and the energy level ranges from about 0.8 J to about2.0 J. In the present process, the connection members are held togetherin a vice, and the laser beam diameter is approximately 0.011″ (0.279mm). The laser beam is applied along the edge of connection members 204a-204 d in a longitudinal manner incrementing to the left or to theright. Alternatively, other welding patterns are used to edge-weldconnection members 204 a-204 d. In some embodiments, the connectionmembers are welded along the horizontal axis, perpendicular to the edgesof the connection members 204 a-204 d. (As shown in cross-wise edge-weld801 c).

Edge-connecting connection members 204 a, 204 b, 204 c, and 204 d toeach other provides a better electrical connection than crimping themtogether. Moreover, edge-connection 801 creates a substantially flat,front surface area on the end of the connection members for attachmentof a feedthrough terminal or a ribbon connection member (not shown).

FIGS. 13-15 show other embodiments of various connection memberstructures and anode layouts that are used for edge-connecting as shownin FIG. 12. In each embodiment shown, anode foils 203 a-203 c each havea thickness of 0.004″ (0.1016 mm) and each cathode 202 and paperseparator 201 layer has a combined thickness of 0.002″ (0.0508 mm).These thicknesses are exemplary and for the purpose of describing thevarious example connection member structures. In some embodiments, thevarious structures and features of FIGS. 12-15 are combined with eachother.

FIG. 13 shows one embodiment in which each capacitor element 105includes two notched anodes, anode 203 a on the top of the stack andanode 203 c on the bottom of the stack and an un-notched middle anode203 b. Some embodiments include two or more top, bottom, and middleanodes. When two or more elements (such as elements 105 c and 105 d) arestacked, the notch of top anode 203 a of lower element 105 c and thenotch of bottom anode 203 c of upper element 105 d define a major notch920. Each major notch, such as major notch 920, receives connectionmembers 904 a, 904 b, and 904 c so that the connection members do notcause a bulge in the anode stack. Each capacitor element 105 a-105 c hasrespective connection member 904 a-904 c attached to it by micro-stakingor other attachment method at respective joints 911 a-911 c.

In this embodiment, each connection member 904 a-904 c is block-shapedand has a height 904 h of approximately 0.014″ (0.3556 mm). This allowseach connection member to fill the space created by the 0.004″ (0.1016mm) anodes and the 0.0012″ (0.0305 mm) cathode 201, and by separators202. In other embodiments, different thicknesses of anodes, cathodes,paper, and connection members are used.

In one embodiment, each connection member 904 a-904 c includes fourfaces 910, 912, 913, and 914. In one embodiment, adjacent faces (such as912 and 913) are perpendicular to each other. In some embodiments, otherangles and shapes are used. Back face 913 abuts or confronts the edgeface of top anode 203 a of lower capacitor element 105 c and the edgeface of bottom anode 203 c of upper element 105 d. Top and bottom faces912 and 914 abut the major surfaces of adjacent middle anodes 203 b.

Each connection member 904 a-904 c is positioned and sized to fit withinthe notches of anodes 203 a and 203 c so that there is no overhang ofthe connection member over the edge of the anodes (in one embodiment,each connection member is 0.050″ (1.27 mm) deep) and so that the exposedfront face 910 of each connection member is substantially flush andevenly aligned and substantially co-planar with its neighboringconnection members and with the edge of anode 203 b, forming a flatfrontal surface area. This flat surface provides an excellent surfacefor performing laser edge-welding or other edge-connecting.

Each connection member 904 a-904 c is edge-connected to its neighboringconnection members at their respective exposed front faces 910 a-910 c.Since there is no need to squeeze connection members 904 a-904 ctogether before they are edge-connected, less stress is put on theconnections 911 a-911 c.

FIG. 14 shows one embodiment in which each capacitor element 105includes one notched anode 203 a for receiving connection members 1001 aand 1001 b without causing a bulge in anode stack 203. Each capacitorelement 105 a and 105 b has respective connection member 1001 a and 1001b attached to it by micro-staking or other attaching method at a weldjoint 1010.

In this embodiment, each connection member 1001 a and 1001 b is abracket-shaped member and includes a cut-out section 1002, which givesconnection members 1001 a and 1001 b a stepped-shaped or L-shaped bodyhaving two surfaces at right angles to each other. The L-shaped bodyincludes a first section 1003 and a second, thicker section 1004. Firstsection 1003 provides a generally planar surface 1020 for attaching to amajor surface 1021 of anode 203 b, while an upper face of section 1003abuts the lower major surface of anode 203 c. Section 1003 includes aback face 1022 which abuts the edge face of anode 203 a. In oneembodiment, first section 1003 has a thickness 1003 t of approximately0.004″ (0.1016 mm), which is approximately the same thickness as anode203 a. Section 1003 has a length 1007 t of approximately 0.050″ (1.27mm).

Second section 1004 provides a surface substantially perpendicular tosurface 1020 of section 1003. The inner surface or face 1009 of section1004 overhangs and confronts the edge faces of anodes 203 b and 203 c.An outer face 1008 of section 1004 provides an exposed surface for beingedge-connected to its neighboring connection members. In one embodiment,second section 1004 has a thickness 1004 t of approximately 0.014″(0.3556 mm), which is approximately the same thickness as the totalthickness of anodes 203 a, 203 b, 203 c, cathode 201, and separator 202.This provides that each connection member is flush with and abutting thenext connection members in the capacitor and that an excellent aluminumsurface is exposed for laser edge-welding and other edge-connecting. Inone embodiment, second section 1004 has a width 1006 t of about 0.020″(0.508 mm).

In other embodiments, the size of cut-out 1002 and the dimensions ofsections 1003 and 1004 of connection members 1001 a and 1001 b aregoverned by or proportional to the thickness of the anodes of acapacitor. In general, connection members 1001 are designed to permitsecond section 1004 to overhang and confront the front edge of anodes203 b and 203 c and to lie flush with the next adjacent connectionmember in the capacitor. For example, in one embodiment (not shown),both anodes 203 a and 203 b are notched and connection member firstsection 1003 has a thickness of approximately 0.010″ (0.254 mm) (thusfilling the 0.010″ notch) while second section 1004 still has athickness of approximately 0.014″ (0.3556 mm). In other embodiments,different sized anodes, cathodes, paper, and connection members areused.

Each connection member 1001 a and 1001 b is edge-connected to itsneighboring connection members. Since there is no need to squeezeconnection members 1001 a and 1001 b together before they areedge-connected, there is less stress on the connections 1010 a and 1010b. Furthermore, each connection member takes up less overall space, thussaving space within the capacitor.

In some embodiments, the connection members have a T-shape cross-sectionor other shapes which provide a first section for attaching to the anodefoil and a second section for confronting the front edge of the foil.

FIG. 15 shows one embodiment in which each capacitor element 105includes two notched anodes, anode 203 a on the top of the stack andanode 203 c on the bottom of the stack, and one or more anodes 203 b nothaving notches. Each capacitor element 105 a-105 b has a respectiveconnection member or connection member 1104 a-1104 b attached to it bymicro-staking or other attaching method at respective weld joints 1111a-1111 b. In one embodiment, each connection member 1104 a-1104 b has aheight 1104 h of approximately 0.004″ (0.1016 mm) to approximately matchthe thickness of the anode foil. This leaves a small gap in the notchbetween the connection members. In one embodiment, each connectionmember has a thickness of about 0.005″ (0.127 mm) so that the notch iscompletely filled. In other embodiments, differences in size, anode,cathode, paper, and connection members may be used without departingfrom the scope of the present subject matter.

In this embodiment, each connection member 1104 a-1104 b is originally aflat strip and is wrapped around anode 203 b to cover and confront thefront edge of the anode foil to create a U-shaped cross-section.Alternatively, in some embodiments, each connection member 1104 isoriginally manufactured with a U-shaped profile or cross section and isplaced into a position as shown.

Each connection member 1104 a-1104 b has an inner surface 1103 and anouter surface 1105. Inner surface 1103 includes a first section 1108abutting a major top surface of middle anode 203 b, a second section1110 abutting a major bottom surface of anode 203 b, and a third section1109 confronting an edge face of anode 203 b. Surface section 1109 issubstantially perpendicular to sections 1108 and 1110, while sections1108 and 1109 are substantially parallel to each other. In oneembodiment, surface 1110 is attached to anode 203 b.

Each connection member 1104 fits within the notches of anodes 203 a and203 c so that outside surface 1105 of each connection member is exposedand aligned with its neighboring connection members, thus forming afrontal surface area which is exposed for being edge-connected.

Each connection member 1104 is edge-connected to its neighboringconnection members. Since there is no need to squeeze connection members1104 a-1104 b together before they are edge-connected, there is lessstress on the connection member-to-anode connection 1111 a-1111 b.

Referring again to FIG. 2 and as discussed above, in one embodimentanode foils 203 a-203 c are high formation voltage anode foils. In oneembodiment, high formation voltage foils are anode foils having aformation voltage of approximately 441 volts or greater. In oneembodiment, the high voltage anode foil comprises an anode foil having aformation voltage between approximately 441 volts and approximately 600volts. In one embodiment, the high voltage anode foil comprises an anodefoil having a formation voltage of approximately 600 volts. In anotherembodiment, the high voltage anode foil comprises an anode foil having aformation voltage of approximately 600 volts to approximately 880 volts.Other embodiments include other high formation anode foils and will bediscussed below. As noted above, some embodiments of the present subjectmatter include low and medium formation voltage foil.

FIG. 16 shows an enlarged perspective view of anode foil 203 a accordingto one embodiment of the present subject matter. Anode 203 a includesopposing surfaces 1602 and 1604 and a set of perforations 1606 p whichextend through anode foil 203 a from surface 1602 to surface 1604.Surfaces 1602 and 1604 include respective sets of surface cavities (ordepressions) 1608 and 1610, which have generally cylindrical, conical,or hemispherical shapes. However, the anode foils are not limited to anyparticular cavity form, class of cavity forms, or combination of cavityforms. For instance, some embodiments include a porous structure havingonly cavities. Some embodiments include only perforations. Otherembodiments use tunnel-etched, core-etched, and/orperforated-core-etched foil structures. Other embodiments utilize otherfoil compositions and classes of foil compositions.

On the major surfaces of anode foil 203 a are oxide layers 1612 and1614. Oxide layers 1612 and 1614 are the dielectric layers of thecapacitor. The dielectric layer separates the anodes from the cathodes.Examples of suitable oxide layers include metallic oxides such asaluminum oxide (Al₂O₃). In one embodiment, layers 1612 and 1614 have athickness sufficient to withstand approximately 441 volts or greater. Inone embodiment, layers 1612 and 1614 have a thickness sufficient towithstand up to 600 volts. Other embodiments withstand 600 volts to 800volts or greater. In one embodiment, dielectric layers 1612 and 1614have a thickness conforming to and covering the etched surface to aheight of at least 540 nm. In some embodiments, the dielectric layerranges from approximately 573 nm to approximately 1200 nm. In oneembodiment, the anode layers 203 a-c have a dielectric thicknesssufficient to withstand approximately 455 volts to approximately 575volts during operation. In additional embodiment, layers 203 a-c have adielectric thickness sufficient to withstand between about 490 volts andabout 540 volts during operation. Other embodiments withstand from about500 volts to about 530 volts during operation. One example is able towithstand about 515 volts during operation.

In one embodiment, dielectric layers on anodes 203 a-c have a thicknessconforming to and covering the etched surface to a height of betweenapproximately 455 nanometers and about 575 nanometers. In someembodiments, the dielectric layer ranges from approximately 490nanometers to about 540 nanometers. Other embodiments range betweenabout 500 nanometers and about 530 nanometers. One embodiments includesapproximately 515 nm. However, due to the nature of the formation of adielectric surface, it should be noted that variations in the thicknessof coatings are substantial.

The present subject matter is useful to produce a capacitor stack with ahigh energy density, due in part to the improved surface shape of theanode. An improved surface area increases the surface area of theelectrodes without increasing the overall size of the capacitor stack.In various embodiments, the present subject matter is capable ofcreating a capacitor with a delivered energy density of from about 5.1joules per cubic centimeter of capacitor stack to about 6.5 joules percubic centimeter of capacitor stack. Additional embodiments deliverenergy density of from about 5.5 joules per cubic centimeter ofcapacitor stack volume to about 6.1 joules per cubic centimeter ofcapacitor stack volume. One example delivers about 5.8 joules per cubiccentimeter of capacitor stack volume.

FIG. 17A shows a flowchart of a method 1700 for preparing an anode foilfor use in a capacitor according to one embodiment of the presentsubject matter. In block 1702, the method includes providing an anodefoil. In block 1704, the method includes etching the anode foil. Inblock 1706, the method includes forming a dielectric layer on the anodefoil.

In various embodiments, the etching of block 1704 includes core-etchingthe foil, tunnel-etching the foil, perforating the foil and combinationsand permutations of these techniques. In some embodiments, perforationssuch as perforations 1606 p discussed above are formed using lasers,chemical etchants, or mechanical dies, for example. Example cavities1608 and 1610 could also be formed using lasers. Some embodimentstunnel-etch the foil, other embodiments provide other known methods ofproviding a porous or etched foil. In some embodiments, a porous anodestructure is constructed using other roughening or etching techniques.

In one embodiment, forming a dielectric layer comprises forming a layerof Al₂O₃ having a thickness in the range of 573 nm to 1200 nm on theanode foil (assuming a dielectric growth rate of 1.3-1.5 nm/V). In oneembodiment, the dielectric layer is formed on the anode before thecapacitor stack is constructed.

In one embodiment, forming the dielectric layer includes applying acurrent through the anode and raising the voltage to the rated formationvoltage. In one embodiment, the formation voltage is 441 volts. In otherembodiments, the forming voltage is 450, 500, 550, 600, and 600-800volts, and other voltages ranging from approximately 441 toapproximately 800 volts or greater. The current causes a dielectricAl₂O₃ to form on the surface of the foil. Once the formation voltage isreached, the capacitor is held at that voltage until a leakage currentstabilizes at a pre-determined level. By monitoring the rising voltageand/or the leakage current, the oxide formation can be estimated. Oncethe preset voltage is reached, it plateaus, in which case a current dropensues in order to balance the increasing resistance of oxide filmgrowth. The process is complete when the current drops to apre-specified value.

Some embodiments combine etching and dielectric forming so that theetching and dielectric forming are done simultaneously.

In one embodiment, method 1700 results in an aluminum anode foil havinga formation voltage between approximately 441 volts and approximately600 volts. In various embodiment, this includes a foil having aformation voltage of approximately 441, approximately 450, approximately500, approximately 550, approximately 600, and approximately 600 voltsto approximately 800 volts or greater. Varying embodiments form adielectric at approximately 600 volts to approximately 760 volts. In oneembodiment, a dielectric thickness sufficient to withstand between about653 volts and about 720 volts develops during formation. Otherembodiments withstand from about 667 volts to about 707 volts duringformation. One example is able to withstand about 687 volts duringformation.

FIG. 17B illustrates an example process 1750 for the anodization ofaluminum electrolytic capacitor foil, according to the present subjectmatter. In varying embodiments, the present subject matter is capable ofproducing anodized aluminum electrolytic capacitor foil at a formationvoltage from about 200 volts to about 760 volts, which can result in acapacitor with a working voltage from about 150 volts to about 570volts. Additionally, the present subject matter is capable of producingan aluminum electrolytic capacitor foil which can deliver about 5.3joules per cubic centimeter of capacitor stack volume to about 6.3joules per cubic centimeter of capacitor stack volume, at a voltage ofbetween about 150 volts to about 570 volts.

Varied processes can be utilized to produce the aluminum foil of thepresent subject matter. For example, one process includes forming ahydrous oxide layer on an aluminum foil by immersing the foil in boilingdeionized water 1752. The aluminum foil is also subjected toelectrochemical anodization in a bath containing an anodizingelectrolyte 1754 composed of an aqueous solution of boric acid, aphosphate, and a reagent. Additionally, the anodizing electrolytecontains a phosphate. In various embodiments, the anodizing electrolyteis at a pH of approximately 4.0 to approximately 6.0. In some examples,the foil is passed through a bath containing a borax solution 1756.Borax, in various embodiments, includes a hydrated sodium borate,Na₂B₄O₇.10H₂O, and is an ore of boron.

In varying embodiments, the foil is reanodized in the boricacid-phosphate electrolyte previously discussed 1758. In variousembodiments of the present subject matter, the process produces astabilized foil suitable for oxide formation of up to approximately 760volts.

In various embodiments, the anodizing electrolyte used in block 1754 and1756 contains about 10 grams per liter to about 120 grams per liter ofboric acid and approximately 2 to approximately 50 parts per millionphosphate, preferably as phosphoric acid, and sufficient alkalinereagent to lower the resistivity to within approximately 1500 ohm-cm toapproximately 3600 ohm-cm and increase the pH from about 4.0 to about6.0 for best anodization efficiency and foil quality.

In some embodiments, the borax bath contains 0.001 to 0.05 moles/literof borax. Because the anodizing electrolyte is acidic, in variousembodiments, the borax bath is buffered with sodium carbonate to preventlowering of the pH by dragout of the acidic electrolyte. Additionally,in various embodiments, the borax bath is buffered to lower itsresistivity. In one example, the pH of the bath is from about 8.5 toabout 9.5, and the temperature is at least approximately 80 degreesCelsius. In varying embodiments, the sodium concentration isapproximately 0.005 to approximately 0.05M, preferably about 0.02 M. Itshould be noted that concentrations of less than approximately 0.005Mare too dilute to control properly, and concentrations aboveapproximately 0.05M increase the pH, resulting in a more reactivesolution which degrades barrier layer oxide quality.

In varying embodiments of the present subject matter, the presence of atleast approximately 2 parts per million phosphate in the acidicanodizing electrolyte is critical. For example, this presence initiatesstabilization of the foil so that solely hydrous oxide dissolves in thealkaline borax bath, without damage to the barrier layer dielectricoxide. In varying embodiments, this lowers ESR (equivalent seriesresistance) of the anodized foil.

Additionally, in various embodiments, when the foil is reanodizedfollowing the alkaline borax bath, the foil surface is alkaline andreacts electrochemically with the phosphate, which, in variousembodiments, results in the incorporation of phosphate into thedielectric oxide. In varying examples, the alkaline foil surfaceincludes a an alkaline metal aluminate, and in one embodiment includes asodium aluminate. It should be noted that the amount of allowablephosphate in the anodizing electrolyte, in various embodiments, isinversely proportional to the voltage at which the foil is beinganodized. For example, in one embodiment, using greater thanapproximately 24 parts per million results in failure during oxideformation at around 650 volts. In embodiments where approximately 50parts per million of phosphate is exceeded, the electrolyte scintillatesat the foil interface, resulting in damaged, unstable foil. One benefitof the present subject matter is that an electrode is produced which cantolerate a high formation voltage without scintillation at the boundarylayer of the foil. It should be noted that anodization temperatureshould be maintained from about 85 degrees Celsius to about 95 degreesCelsius, as variance outside of these values results in a the barrierlayer oxide of lower quality, and foil corrosion.

Various aspects of the present subject matter include performanceproperties which enable the capacitor to function as a single capacitorin an implantable cardioverter defibrillator 1760. For example, byconstructing the capacitor stack with the methods and apparatuscontained in these teachings, one may construct a capacitor which issuited for use as the sole capacitor used for powering therapeuticpulses in an implantable cardioverter defibrillator. By using a singlecapacitor, instead of two capacitors which are connected in series, thepresent subject matter contributes to weight and size reductions.

FIG. 18 shows a partially exploded view of a capacitor 2018 according toone embodiment of the present subject matter. Capacitor 2018 includesone or more features of capacitor 100 of FIG. 1, and some details willbe omitted in the present description. In this embodiment, the capacitorincludes a case 2020 defining a chamber 2022, in which is placed acapacitor stack 2024.

Case 2020 includes a base 2026 and a lid 2028 overlying and resting onan upper rim of base 2026. Stack 2024 has a face 2030 and a top surface2032. Stack 2024 has a cutout region 2034 at its periphery, with cutoutregion 2034 being positioned when the stack 2024 is installed in case2020 to provide space for electrical connections. An anode feedthroughpost 2036 passes through to stack 2024 and is electrically insulatedfrom case 2020. The capacitor stack 2024 is covered with insulating tape2038. A space 2040 exists between the lid 2028 and the top surface 2032of the stack 2024 and between the face 2030 of the stack 2024 and alateral wall of the base 2026 of the case 2020. In some embodiments,space 2040 is a line-to-line interference fit between portions of stack2024 and case 2020. In other embodiments, space 2040 is a gap or openingwithin the case and between the stack and the case.

Capacitor stack 2024 includes anode assemblies and cathode assemblies,with separator layers interposed therebetween.

FIG. 19 illustrates an exploded view of capacitor stack 2024 accordingto one embodiment. Stack 2024 includes a plurality of layers 2120 whichinclude at least one first electrode comprised of an anode stack 2100,at least one separator 2200, and at least one second electrode comprisedof one of cathode stacks 2300. The separator 2200 separates each anodestack 2100 from each cathode stack 2300.

FIG. 20 illustrates an exploded view of one example of an anode stack2100. The anode stack 2100 includes a plurality of anode layersincluding conductive layers 2115 consisting of an upper conductive layer2110, a middle conductive layer 2114, and a lower conductive layer 2116as well as an anode-separator layer 2090. Each conductive anode layerhas a first edge 2111, 2121, 2131, and 2141, respectively. Each anodelayer also includes a clearance area defined by a second edge 2112,2122, 2132, 2142. Each anode layer also includes an optional second edge2113, 2123, 2133, 2143, respectively. The anode stack 2100 furtherincludes an edge connection member such as edge clip 2150 for use ininterconnecting the anode layers in adjacent layers of the capacitorstack 2024.

FIG. 21 illustrates a portion of an assembled anode stack 2100. Theclearance area defined by the second edge 2142 of the anode-separator2090 leaves the upper surface 2154 of the edge clip 2150 exposed forcontact with a connection member such as an adjacent edge clip 2150 ofan adjacent layer 2120.

FIG. 22 illustrates a separator 2200 which separates the anode stack2100 from the cathode stack 2300 (FIG. 19). The separator 2200 includesa first edge 2251 a clearance area defined by a second edge 2252 and aflat edge 2253. The clearance area of the separator 2200 allows a sideportion of the edge clip 2150 (FIG. 20) to extend past the separator toreach an edge clip of an adjacent anode stack 2100 (FIG. 19). Theseparator 2200 is, in one option, made from a roll or sheet of separatormaterial. Suitable materials for the separator material include, but arenot limited to, pure cellulose or Kraft paper. Other chemically inertmaterials are suitable as well, such as porous polymeric materials. Theseparator 2200 is cut slightly larger than the anode layers (or cathodelayers) to accommodate misalignment during the stacking of layers, toprevent subsequent shorting between electrodes of opposite polarity, andto act as an outermost edge for alignment.

FIG. 23 illustrates an exploded view of an embodiment of a cathode basestack 2050 including a cathode conductive layer 2060 and acathode-separator layer 2070. In this embodiment, cathode conductivelayer 2060 includes one or more legs 2054 a, 2054 b, 2054 c, 2054 dextending from the flat edge 2363. The cathode conductive layer 2060also includes a cathode extension member 2062 for coupling the capacitorstack 2024 to the case 2020 (FIG. 18). Cathode legs 2054 a, 2054 b, 2054c, 2054 d and cathode extension leg 2062 extend beyond the dimensionsdefined by the inside of the case 2020 during intermediate steps in themanufacturing process and are later formed to fit within the case. Thecathode conductive layer 2060 includes a first edge 2361 inset from thefirst edges of the anode layers 2110, 2114, 2116, and 2090 (FIG. 20) andinset from the second edges of the anode layers 2110, 2114, 2116, and2090. The conductive layer 2060 also includes a flat edge 2363 insetfrom the flat edges of the anode layers 2110, 2114, 2116, and 2090.

Cathode-separator layer 2070 is also provided and includes a first edge2371, a clearance area defined by a second edge 2372, a flat edge 2373and an extension edge 2374. The cathode conductive layer 2060 includes afirst edge 2361 inset from the first edge 2371 of the cathode-separatorand inset from the second edges of the cathode-separator layer 2070. Thecathode conductive layer 2060 also includes a flat edge 2363 inset fromthe flat edges of the cathode-separator layer 2070. The inset edge 2361of the cathode conductive layer 2060 and the clearance area of thecathode-separator layer 2070 allows a portion of the edge clip 2150(FIG. 20) to extend past the cathode conductive layer 2060 and thecathode-separator layer 2070 to reach an edge clip 2150 (FIG. 20) of anadjacent anode stack.

Referring to FIGS. 24-27, examples of cathode stacks 2300 are shown.Cathode stacks 2300 include in one embodiment, cathode stacks 2301,2302, 2303, 2304. Each cathode stack 2301, 2302, 2303, 2304 includescathode layers comprising a cathode conductive layer 2060 and acathode-separator layer 2070. In this embodiment, each cathode stack2301, 2302, 2303, 2304 conductive layer 2060 includes an extensionmember such as a leg 2060 a, 2060 b, 2060 c, or 2060 d respectively.Cathode legs 2060 a-2060 d on each cathode stack 2301, 2302, 2303, 2304extend beyond the dimensions defined by the case 2020 (FIG. 18) duringintermediate steps in the manufacturing process and are later formed tofit within the case. In one embodiment, each leg 2060 a-2060 dcorresponds to leg 2054 a, 2054 b, 2054 c, 2054 d, respectively, on thecathode base layer stack 2050, as will be discussed further below. Eachcathode stack 2301, 2302, 2303, 2304 includes a cathode conductive layer2060 having a first edge 2361, which when stacked, is inset from thefirst edge 2141 of the anode separator 2090 (FIG. 20) and inset from thesecond edge 2142 of the anode separator. Further details of cathodestacks 2300 will be described below.

In one embodiment of the present subject matter, the capacitor stack2024 described above is aligned to provide for optimal surface area ofthe capacitor.

FIGS. 28A, 28B, and 29 illustrate external alignment mechanisms 2408,2406, 2400 used to assemble anode stack 2100, cathode stack 2300, andcapacitor stack 2024, respectively, in accordance with one embodiment.Each of the external alignment mechanisms 2408, 2406, 2400 includes aplurality of precisely placed alignment elements 2500.

The alignment elements 2500 in this embodiment are vertically placedalignment elements 2501, 2502, 2503, 2504, which extend from a base2402. The base 2402 supports components thereon, while the alignmentelements 2501, 2502, 2503, 2504 align the components while thecomponents are being stacked therein. The external alignment mechanism2400 optionally includes a first recess 2520, which is sized andpositioned to receive a clip, as further discussed below. In anotheroption, the external alignment mechanisms 2406, 2408 each include asecond recess 2506, 2508, respectively, in the base 2402, as furtherdiscussed below.

Referring to FIG. 29, a capacitor stack 2024 is assembled within thealignment apparatus 2400. The capacitor stack 2024 includes theplurality of layers 2120. Each layer 2122 of the plurality of layers2120 includes at least one first electrode stack, at least one separator2200 (FIG. 19) and at least one second electrode stack. Each firstelectrode stack, second electrode stack and each separator 2200 isaligned relative to the position of the alignment elements 2501, 2502,2503, and 2504. Optionally positioned within the optional channel 2600is a fastener 2610, which is for wrapping around a portion of thecapacitor stack 2024 once the first electrode stacks, separators 2200and second electrode stacks have been stacked and aligned. Placing thefastener 2610 in the channel 2600 of the external alignment mechanism2400 positions the fastener 2610 below the aligned capacitor stack 2024to maintain flatness of the capacitor stack 2250, for example, forfurther processing. Alternatively, or in addition to, the optionalchannel 2600 allows for a gripping device such as pliers to be slippedunder the capacitor stack 2250. In addition, precise alignment of thecapacitor stack 2250 is maintained by the alignment elements 2500 whenwrapping the capacitor stack 2250.

FIG. 30 illustrates a top view of anode stack 2100 within the anodeexternal alignment mechanism 2408, as described in FIG. 28A. To alignthe anode stack 2100, each conductive layer 2110, 2114, 2116, (FIG. 20)is placed in the recess 2508. The anode separator 2090 (FIG. 20) isplaced over the conductive layers 2110, 2114, 2116 and is alignedrelative to the alignment elements 2501, 2502, 2503, 2504 by positioningthe separator such that the first edge 2141 and the flat edge 2143extend to contact each of the alignment elements 2501, 2502, 2503, 2504.The second recess 2508 allows the anode separator 2090 to be alignedrelative to the conductive layers 2110, 2114, 2116. The alignmentelements 2501, 2502, 2503, 2504 concentrically align the separator 2090relative to the conductive layers 2110, 2114, 2116 (FIG. 20).

In one embodiment, the anode external alignment mechanism 2408 includesa recess 2520. The recess 2520 receives a portion of the edge clip 2150(FIG. 20) that extends beyond the anode stack 2100 and allows theconductive layers 2115 of the anode stack 2100 to lay flat, one on topof the other within the anode external alignment mechanism 2408. In oneembodiment, the anode stack 2100 is staked after being aligned in thismanner.

FIG. 31 illustrates one embodiment in which the anode stack 2100 isremoved from the anode external alignment mechanism 2408 (FIG. 30) andstaked so that the conductive layers of the anode stack 2100 form ananode chip. In one embodiment, the anode stack is staked as describedabove, and incorporated herein by reference. In one embodiment, thestaking locations 2102 of the anode stacks 2100 in the capacitor stack2024 (FIG. 18) are distributed so that anode stacks 2100 in adjacentlayers have staking locations that are offset from one another, as shownin FIG. 32. In one embodiment, the anode stack 2100 is pressed afterbeing staked to help reduce warpage and to reduce the overall height ofthe anode stack 2100. In one embodiment, the anode stack 2100 is pressedto a specific, predetermined height.

FIG. 33 illustrates a cathode stack 2300 within a cathode externalalignment mechanism 2406. The same method is used to align the cathodeconductive layer 2060 and cathode separator layer 2070 of the cathodestacks 2050, 2301, 2302, 2303 and 2304, as was used to align the anodestack 2100 (FIG. 30). The cathode conductive layer 2060 is disposedwithin the recess 2506, and the cathode separator layer 2070 is alignedrelative to the alignment elements 2501, 2502, 2503, 2504. Since thealignment elements 2501, 2502, 2503, and 2504 are placed in the samelocation for the anode external alignment mechanism 2408, the cathodeexternal alignment mechanism 2406, and the external alignment mechanism2400 (FIG. 29), allows for the stacks 2100, 2300 to be better aligned toone another. This helps to reduce variances in alignment which mayresult from varying tolerance stack ups between layers of the assemblyand the alignment mechanism used.

In one embodiment, the cathode separator layer 2070 is aligned relativeto the plurality of alignment elements 2500 by stacking the cathodeseparator layer 2070 so that edge 2371 and flat edge 2373 extend tocontact each of the alignment elements 2501, 2502, 2503, and 2504. Whilealigned, the cathode separator layer 2070 is coupled to the cathodeconductive layer 2060, for example, with adhesive. In one embodiment,each cathode stack 2300 is pressed to help reduce warpage and thus toreduce the overall height of the capacitor stack 2024 (FIG. 18).

FIG. 34 illustrates a capacitor stack 2024 within an external alignmentmechanism 2400. In this embodiment, the capacitor stack 2024 includes aplurality of layers 2120, including anode stacks 2100 (FIG. 20), andcathode stacks 2300 (such as cathode stacks 2050, 2301-2304 in FIGS.23-27), which were each individually aligned with the anode externalalignment mechanism 2408 and the cathode external alignment mechanism2406, respectively. The anode stacks 2100 and the cathode stacks 2050,2301-2304 are aligned relative to the alignment elements 2500 using oneor more outer edges of the cathode separators 2070 (FIGS. 23-27) and oneor more outer edges of the anode separators 2090 (FIG. 20). In oneembodiment, capacitor stack 2024 includes separators 2200 (FIG. 22) andthe alignment elements 2501, 2502, 2503, 2504 further align theseparator 2200 relative to the anode stacks 2100 and the capacitorstacks 2300 using an outer edge of the separator 2200 (FIG. 22). In someembodiments, separators 2200 are omitted and capacitor stack 2024 isaligned relative to the alignment elements 2500 using only one or moreouter edges of the cathode separators 2070 (FIGS. 23-27) and one or moreouter edges of the anode separators 2090 (FIG. 20).

In one embodiment, a fastener 2610 is wrapped around a portion of thestack 2024 to retain the alignment of the layers 2120 relative to oneanother. In one embodiment, fastener 2610 comprises tape that is wrappedaround a central portion of the capacitor stack 2024. Optionally, thecapacitor stack 2024 is then clamped and annealed, with or without thefastener 2610. The channel 2600 optionally allows for a tool and/or arobot to be disposed under the stack 2024.

In some embodiments, the anode stack 2100 and the cathode stacks 2050,2301-2304 are aligned relative to one another within the case 2020,instead of using the external alignment mechanism 2400, and then arecoupled to one another in the aligned position. For instance, an outeredge of a separator of the anode stack 2100 (FIG. 20) and an outer edgeof a separator of the cathode stacks 2050, 2301-2304 (FIGS. 23-27) wouldcontact an interior surface of the case 2020, and would be alignedtherein.

Among other advantages, one or more embodiments of the alignmentmechanism described provide for a capacitor making efficient use ofspace within the case, permit increased anodic surface area, andincreased capacitance for a capacitor of a given set of dimensions.Variation in the outer dimensions of one capacitor stack to anothercapacitor stack is reduced because each is formed within alignmentelements positioned the same manner. Dimensional variations in thecapacitor stack resulting from variation in the reference points fromcase to case or alignment apparatus to alignment apparatus areeliminated. This provides improved dimensional consistency in productionand allows for reduced tolerances between the capacitor stack and thecapacitor case. This allows for more efficient use of space internal tothe capacitor case. Each first electrode stack, second electrode stackand each separator is aligned relative to the position of the alignmentelements.

Moreover, the example of the capacitor stack structure described aboveprovides for greater anodic surface area since, by aligning to theseparator, the anode surface area is optimized by not having to provideextraneous alignment notches or other alignment features on the anodefoil itself which decrease the anode surface area.

Since the external alignment mechanism is exterior to the case, bettervisual observation of the alignment of each electrode stack andseparator is provided. Furthermore, multiple points are used to make thealignment, reducing the effect of the tolerance stack up between theconductive layer or separator being aligned and the alignment element atany one position. This also facilitates for alignment of componentswhich during certain steps in the manufacturing process have portionswhich extend beyond the dimensions defined by the case and are laterformed to fit within the case.

In some embodiments, the edges of the cathodes and anodes describedabove are generally co-extensive or aligned with each other within stack2024. In other embodiments, capacitor stack 2024 includes anode andcathode layers having at least partially offset edges.

FIG. 35 shows a planar view of a cathode stack 1800 according to oneembodiment. The capacitor stack 1800 includes an anode layer 1801, aseparator 1802, and a cathode layer 1803 that are configured in alayered structure analogous to capacitor stack 24 described above. Thebottom surface in the FIG. is the anode layer, and the top surface isthe cathode layer with the paper separator interposed therebetween. Theseparator includes two paper separators impregnated with an electrolytethat conducts current between the anode and cathode layers.

Some cutting processes used to make anode and cathode foil layers canproduce burrs on the foils that can result in a short circuit if a burron an anode layer edge portion makes contact with an adjacent cathodelayer or vice-versa. When the dimensions of the cathode and anode layersare the same so that the edges of each layer are aligned, a burr on acathode layer edge portion can then contact a burr on an anode layeredge portion. Burrs on overlapping edge portions of the anode andcathode layers may then make contact and cause a short circuit bytraversing only half of the thickness of the paper separator between thetwo layers.

Accordingly, in one embodiment, the capacitor stack is constructed withlayers having edge portions that are offset from one another. In oneembodiment, this is done by having a cathode layer with a differentdimension than the anode layer so that portions of their edges areoffset in the layered structure (i.e., either the anode layer or thecathode layer is smaller than the other). The anode and cathode layersmay be of the same general shape, for example, but of different surfaceareas so that the perimeter of one layer is circumscribed by theperimeter of the other layer.

The capacitance of an electrolytic capacitor results from the chargeseparation between the electrolyte and the anode layer so that alteringthe surface area of the cathode layer does not appreciably affect thecapacitance of the device. Such an arrangement is shown in FIG. 35 wherethe cathode layer 1803 is of the same general shape as the anode layer1801 but with a smaller surface area such that the edge portions of thecathode layer are inwardly offset from the anode layer edges. In thisstructure, only an edge burr on the cathode layer that traverses theentire thickness of the paper separator can produce a short circuit.This is in contrast to the case where the edge portions of the twolayers are aligned rather than being offset. Offsetting the edgeportions results in a greater tolerance for edge burrs and allows a lessconstrained manufacturing process.

FIG. 36 shows a cross-sectional schematic of capacitor stack 1800. Thecapacitor is made up of a plurality of capacitive elements that arestacked on one another with each capacitive element being a layeredstructure capacitor such as shown in FIG. 35. The anode layers 1801 arestacked on cathode layers 1803 in alternate fashion with paper separator1802 interposed between each anode layer and each cathode layer.

Varying embodiments use assorted combinations of anodes and cathodes.For example, some embodiments of the capacitor stack include from about16 planar cathode layers to about 20 substantially planar cathodelayers, and from about 52 substantially planar anode layers to about 64substantially planar anode layers, and one or more substantially planarseparator layers. In one example, approximately 58 anode layers areused, and approximately 20 cathode layers are used, with each cathodelayer separated from anode stack by approximately 40 separator layers.In this example embodiment, two anode layers have been removed from theexample to reduce the thickness of the capacitor stack. In varyingexamples, this is due to packaging considerations. The example alsoincludes a stack which alternates between one cathode and three anodelayers, also called an anode stack. The anode layers are not separatedby a separator layer, in various embodiments, to save space.

FIG. 37 shows a capacitor stack 1900 according to one embodiment.Capacitor stack 1900 includes multiple porous anode layers 1901. Themultiple layers result in a greater surface area exposed to the liquidelectrolyte and a greater capacitance for each element. Three anodelayers 1901 a-1901 c are shown in the FIG. which are stacked togetherwith a paper separator 1902 and cathode layer 1903 on each side of thestack. The liquid electrolyte flows through perforations in the anodelayers to reach the oxide layers of each layer. The edge portions ofeach cathode layer 1903 are inwardly offset from the edge portions ofeach overlying and underlying anode layer 1901.

In one embodiment, the offset structure described above can beincorporated into a cylindrical capacitor. For instance, the anode andcathode layers are cut from a sheet in a desired width and length. Thecathode layer is made narrower than the anode layer so that the edges ofthe cathode layer are inwardly offset from the anode layer edges. Thecylinder configuration is then produced by rolling the layers intoconcentric anode and cathode layers that are separated by electrolyte.

Offsetting of anode layer and cathode layer edge portions may beaccomplished by using a variety of differently shaped and/or dimensionedcathode or anode layers.

In some embodiments, the cathode layer reduction ratio relative to theanode layer is limited. The electrical equivalent circuit of anelectrolytic capacitor is the series connection of an anodic capacitancedue to the charge separation that occurs between the anode layer and theelectrolyte across the dielectric layer, an equivalent series resistanceof the capacitor or ESR, and a cathodic capacitance due to the chargeseparation that occurs between the cathode layer and the electrolyte.

When a capacitor is charged to its rated voltage, the voltage is dividedand dropped across between the cathodic capacitance Cc and the anodiccapacitance Ca. Since the charge stored on cathode layer Qc must equalthe charge stored on the anode layer Qa, then:

-   -   Qa=Qc    -   CcVc=CaVa        where Vc is the voltage dropped across the cathodic capacitance        and Va is the voltage dropped across the anodic capacitance.

The voltage Vc is thus inversely proportional to the cathodiccapacitance. The cathodic capacitance should be large enough so thatonly a small voltage drop occurs across it when a voltage is applied tothe capacitor, with most of an applied voltage being dropped across theanodic capacitance. If the cathode layer is made small enough relativeto the anode layer, the cathode layer's capacitance may be reduced tosuch an extent that when the capacitor's rated voltage is applied anovervoltage condition occurs at the cathode layer with the creation ofoxide and evolution of hydrogen gas.

Accordingly, in one embodiment the cathode layer is limited to thedegree of decrease in surface area relative to the anode layer. In oneembodiment, the cathode layer is kept to a size that keeps theovervoltage at tolerable levels when a rated voltage is applied to thecapacitor. Such a minimum size for a cathode layer will vary, of course,with the capacitor's geometry and its rated operating voltage, but thesize limit can easily be determined empirically.

In one embodiment, for example, flat capacitors used in implantabledefibrillators is designed to operate at a rated voltage of 400 volts,and the ratio of the cathode layer surface area to the anode layersurface area is approximately 0.75 or greater. In some embodiments, theratio is approximately 0.75 to approximately 0.93. In some embodiments,the ratio is approximately 0.93.

In some embodiments, capacitor stack 2024 includes a uniform level ofanode foils in each anode stack 2200. In other embodiments, the numberof anode foils varies from stack to stack.

For instance, FIG. 38 illustrates a cross-section of a capacitor stack2160 according to one embodiment. One example of mixed anode stacks 2102is shown, which includes an anode stack 2100 and a modified anode stack2101. The anode stack 2100 includes at least one conductive layer 2115having a height 2146. The modified anode stack 2101 includes a pluralityof conductive layers 2118 such that the modified anode stack 2101includes at least one more conductive layer than included in the anodestack 2100. The anode stack 2100 and the modified anode stack 2101differ in the quantity of conductive layers in each. In addition, theanode stack 2100 and the modified anode stack 2101 differ in the totalsurface area of each.

The anode stack 2100, also shown in FIG. 39 includes a first conductiveelement 2110, a second conductive element 2112, and a third conductiveelement 2114, and an anode separator 2140. In one embodiment, as shownin FIG. 40, a modified anode stack 2101 includes a first conductiveelement 2110, a second conductive element 2112, a third conductiveelement 2114, and a fourth conductive element 2116, and an anodeseparator 2140, where the modified anode stack 2101 includes at leastone more conductive element than the anode stack 2100. In anotheroption, the modified anode stack 2101 includes one or moreless-conductive elements than the anode stack 2100.

FIG. 41 illustrates another example of mixed anode stacks 2202, whichincludes a first anode stack 2204, a second anode stack 2206, and athird anode stack 2208. The first anode stack 2204 has a plurality ofconductive layers 2215 including a first conductive element 2210, asecond conductive element 2212, and a third conductive element 2214. Inone option, the second anode stack 2206 includes a first conductiveelement 2210, a second conductive element 2212, a third conductiveelement 2214, and a fourth conductive element 2216. The third anodestack 2208 includes a first conductive element 2210, a second conductiveelement 2212, a third conductive element 2214, a fourth conductiveelement 2216, and a fifth conductive element 2218, where the second andthird anode stacks 2206, 2208 include a different number of conductiveelements than the first anode stack 2204. In another option, themodified anode stack 2201 includes one or more less conductive elementsthan the anode stack 2200.

In one embodiment, the first anode stack 2204 has a first surface area,and the second anode stack 2206 has a second surface area, and the firstsurface area is different than the second surface area, for example thesecond surface area is greater than the first surface area. In a furtheroption, the first anode stack 2204 has a first surface area, the secondanode stack 2206 has a second surface area, and the third anode stack2208 has a third surface area. The third surface area is different thanthe first surface area and/or the second surface area, for example thethird surface area is greater than the first surface area and/or thesecond surface area. The surface areas can be modified by modifying thesurface of the conductive elements, for example, by etching. It shouldbe noted that additional combinations of conductive layers and/orsurface areas are contemplated and are considered within the scope ofone or more embodiments of the present subject matter.

Referring to FIG. 42, the anode stack 2100 is coupled with the modifiedanode stack 2101, where there are a variety of ways to couple themodified anode stack 2101 with the anode stack 2100. In one example, thestack 2160 includes one or more connection members such as an edge clip2150 and a modified edge clip 2170, which interconnect the modifiedanode stack 2101 with the anode stack 2100. The modified edge clip 2170,which is coupled with the modified anode stack 2101, has a height 2142that is extended for a slightly higher height of the modified anodestack 2101. The edge clip 2150 coupled with the anode stack 2100 has aheight 2144 suitable for use with the anode stack 2100. The edge clips2150, 2170 permit taller anode stacks to be reliably combined. The edgeclips 2150, 2170 are anodic and are optionally used to increase anodicsurface area of the conductive layers 2115 as the edge clips 2150, 2170require little space within the capacitor stack 2160. The composition ofcells 2290 and modified cells 2292 as further discussed below, can bemodified without requiring changes to other components in the capacitorstack 2160 resulting in greater design flexibility.

Referring again to FIG. 38, the capacitor stack 2160 includes at leastone cell 290, where each cell 2290 includes an anode stack 2100, ananode separator 2140, a cathode stack 2300, and a cathode separator2200. In addition, the capacitor stack 2160 includes at least onemodified cell 292, where each modified cell 292 includes a modifiedanode stack 2101, an anode separator 2140, a cathode stack 2300, and acathode separator 2200. In one option, the cathode stack 2300 and thecathode separator 2200 are substantially the same as included in thecell 2290 and the modified cell 2292, such that the difference in heightbetween the anode stack 2100 and the modified anode stack 2101 is due tothe increase in height of the modified anode stack 2101 resulting fromthe modified anode stack 2101 having a greater number of conductivelayers 2115 than included in the anode stack 2100. In another option,the modified anode stack 2101 of the modified cell 2292 has fewerconductive layers 2115 than the anode stack 2100.

In one embodiment, a plurality of modified cells 2292 is distributedthroughout the capacitor stack 2160 in a manner to optimize use ofexisting cathodic area. In one example, the capacitor stack 2160includes fifteen cells, where at otherwise would be every fifth cell2290, a modified cell 2292 is disposed instead. Since the modified anodestack 2101 of the modified cell 2292 includes at least one moreconductive layer than the anode stack 2100, the resulting example ofcapacitor stack 2160 includes at least three additional conductive anodelayers within the case 20 (FIG. 18), without a substantial increase inthe height of the components therein. For instance, for the capacitorstack 2160, instead of adding an additional anode stack 2100, whichwould have a height of three conductive layers 2115 (FIG. 39), and theheight of an anode separator 2140 (FIG. 39), and the height of aseparator 2200, and the height of a cathode stack and an additionalseparator, only the height of the additional conductive layers 2115 inthe modified anode stack 2101 is added to the height of the capacitorstack 2160.

In other embodiments the modified anode stack 2101 contains one, two,three, four, five, six or more conductive layers 2115 than is includedin each anode stack 2100. Alternatively, more than one type of modifiedanode stack 2101 is included with the capacitor stack 2160.

Referring again to FIG. 42, a stack 2160 is shown which includes cell2290, and modified cell 292. An edge clip 2150 is adjacent the edge clip2170 of an adjacent modified cell 292. The edge clip 2150 is coupled toadjacent modified edge clip 2170. For example, the edge clip 2150 iswelded to the modified edge clip 2170. Where a plurality of cells 2290and modified cells 2292 are provided, a plurality of edge clips 2150,2170 are also provided. The plurality of edge clips 2150, 2170 stack oneon the other such that the bottom surface 2157 of an edge clip 2150 ormodified edge clip 2170 contacts the upper surface 2154 of an adjacentmodified edge clip 2170, or edge clip 2150. The stacked edge clips 2150,2170 provide a larger contact surface 2158 increasing ease of attachmentthereto. Each anode stack 2100 and modified anode stack 2101 remainsessentially flat and do not require the ductility required of otherdesigns to make an electrical connection. The stacked edge clips 2150,2170 provide for layer designs having higher stack composed of lessductile materials previously used, and further provide forinterconnections in less space.

In one embodiment, an upper portion 2153 of the edge clip 2150 ormodified edge clip 2170 is positioned within a clearance area 2112 ofthe first conductive element 2110. A side portion 2152 of the edge clip2150 extends along the edges 2122, 2132 of the second 2112 and third2114 conductive elements, and extends along the edges of separators2200, and further along the edge of the anode separator 2140 of anadjacent modified anode stack 2101. The edge clip 2150 remains separatefrom the cathode stack 2300. The side portion 2152 of the modified edgeclip 2170 extends along the edges 2122, 2132, 2182 of the second 2112,third 2114, and fourth 2116 conductive elements. The side portion 2152also extends along the edges of separators 2200, as well as along theedge of the anode separator 2140 of an adjacent anode stack 2100 ormodified anode stack 2101. The edge clip 2170 remains separate from thecathode stack 2300.

In one or more embodiments, edge clips are utilized and/or connectedtogether as described above for FIGS. 2-15.

In one embodiment, a method is also provided, the method involvingaligning an anode stack, including aligning at least one conductivelayer having a surface and an edge, and aligning a first separatorbetween the anode stack and a modified anode stack. The method furtherincludes aligning at least one modified anode stack with the anodestack, which includes aligning a plurality of conductive layers, whereinthe plurality of conductive layers includes at least one more conductivelayer than included in the anode stack and one of the plurality ofconductive layers having a surface and an edge, and electricallycoupling the anode stack with the modified anode stack.

Several variations for the method are as follows. The method furtherincluding welding an edge clip to the modified anode stack. In anotherembodiment, the method further includes aligning a first modified anodestack and a second modified anode stack, each having a plurality ofconductive layers. In yet another embodiment, the method furtherincludes stacking a first number of layers to form the first modifiedanode stack, and stacking a second number of layers to form the secondmodified anode stack, and the first number of layers is different thanthe second number of layers. In yet another embodiment, the methodfurther includes aligning a second separator between the first modifiedanode stack and the second modified anode stack.

Advantageously, the mixed-anode capacitor stacks described above allowfor a reduction in the volume, thickness, and the mass of the stackwithout a reduction in the deliverable energy, which provides for asmaller overall device size. This results in increased patient comfort,and reduces tissue erosion surrounding the implantable device. Inaddition, reducing the size of the capacitor allows for other criticalcomponent sizes to be increased, for example, the battery, or for othercomponents to be added. A further benefit is that anodic surface area isincreased without requiring additional cathodic area to support theadded anode conductive layers. This allows a boost in capacitance with aminimal increase in thickness of the capacitor. In empirical studies,capacitors that included the modified anode stack showed capacitancevalues of 186 μF, 185 μF, and 186 μF, compared to standard deviceswithout the modified anode stack which had capacitance values of 172 μF,172 μF, and 173 μF.

Referring again to FIG. 34, once stack 2024 is stacked as shown, theanode and cathode layers are interconnected. In one embodiment, one ormore layers are constructed and connected as described following.

FIG. 43 shows further details of capacitor stack 2024 according to oneembodiment of the present subject matter. As described above, thecathode layers 2300 include base foil layer 2050 and a plurality ofsecondary foil layers 2301-2304, here denoted generally as layers 2052.The base layer has a plurality of base tabs 2054 a-2054 d including afirst base tab 2054 a in a first tab position 2056 a, a second base tab2054 b in a second tab position 2056 b, a third base tab 2054 c in athird tab position 2056 c, and a fourth base tab 2054 d in a fourth tabposition 2056 d. The present description is an example. Otherembodiments include more tabs and fewer tabs with varying numbers of tabpositions. Each tab 2054 a-2054 d is electrically coupled to the othertabs 2054 a-2054 d through base layer 2050, which includes at least onetab at each tab location. Each secondary layer 2052 has at least oneextension member or leg 2060 a-2060 d positioned to overlay, beco-extensive with, or match with one of the plurality of tab positions2056 a-2056 c.

In this embodiment, the cathode layers are positioned to include a firstlayer group 2060 a, a second layer group 2060 b, a third layer group2060 c and a fourth layer group 2060 d. Other embodiments have morelayers or fewer layers. The layer groups are in electrical contact witheach other, but spaced apart from the anode tabs 2049 to allow separateconnection of anode layers 2046 without shorting. The layer groupselectrically connect to an external cathode connection or cathode lead2062 which provides an external electrical connection to the case.

Each group of extension members 2060 a-2060 c is positioned to overlayone of a plurality of tab positions 2056 a-2056 d. The plurality ofsecondary layers is portioned into the plurality of the layer groups.The matching tabs of each layer group are located in the same position.For example, each of the matching tabs 2060 a of first layer group 2060a are located in first tab position 2056 a so that the matching tabs2060 a overlay first base tab 2054 a, which is also in first tabposition 2056 a. In other words, from a top view perspective, tabs 2060a are commonly positioned or co-extensive with base tab 2054 a.Secondary layers in each layer group are shown as located in adjacentlayers. Alternatively, the layer groups may comprise secondary layersfrom non-adjacent layers.

FIG. 44 shows another view of the capacitor stack 2024 having matchingtabs of each secondary layer group 2060 folded and welded to thecorresponding tab 2054 of the base layer, forming a plurality of tabgroups 2064. The tab groups 2064 electrically connect to an externalcathode connection or cathode lead 2062 which provides an externalelectrical connection to the case.

The cathode layers 2044 include a first tab group 2064 a, a second tabgroup 2064 b, a third tab group 2064 c and a fourth tab group 2064 d.The tab groups 2064 are also in electrical contact with each other, butspaced apart from the anode tabs 2049 to allow separate connection fromthe anode layers 2046 without shorting. The tab groups 2064 areelectrically connected to the capacitor case 2020 or alternatively maybe insulated from the case 2020.

FIG. 45 shows another view of capacitor stack 2024 showing tab groups2064 folded into position on the top surface 2032 of capacitor stack2024. The tab groups have a reduced thickness and are folded onto thetop of the stack and taped. Alternatively, the tab groups are cut justbeyond the weld and taped against the face 2030 of the stack. Each tabgroup 2064 has a thickness that is less than the sum of the base layerand all the secondary layers.

The thickness of the tab groups are approximately equal to or less thanspace 2040 as previously shown in FIG. 18. As noted above, in someembodiments, space 2040 is merely a line-to-line interference fit. Thepresent cathode structure provides that the cathode interconnections fitwithin the limited room available. Alternatively, the tab groups arelocated in space 2040 between the face 2030 of stack 2024 and the case2020 or base 2026.

In this embodiment, base layer 2050 has four base tabs 2054 a-2054 d andeach secondary layer 2052 has at least one tab 2058 that matches one ofthe base tabs 2054 a-2054 d. The base tabs and matching tabs may bestaked to the foil layer or the tabs may be integral with the foillayer. The layers 2050, 2052 may have two or more tabs. The base tabsare shown with four tabs and the secondary tabs are shown with one tab.In some embodiments, the secondary layers include two or more tabs tocreate redundancy.

The embodiment described above show the base layer and secondary layeras cathode layers. However, the anode layers may also be arranged in asimilar fashion. The anode layers may include a base layer with basetabs and secondary layers with matching tabs either alternatively or inaddition to the cathode layers. The anode layers and cathode layers maybe separated into tab groups and positioned in the space between the topof the stack and the housing and the face of the stack and the housing.The anode layers and cathode layers remain separated from each othersuch as with paper layers. Insulation may also be required between theanode and cathode layers and the case.

FIG. 46 shows a side view of base layer 2050 and secondary layers 2052of a capacitor stack including layer groups such as non-adjacent layergroup 2066 d. The matching tabs 2058 of secondary layers 2052 ofnon-adjacent layer group 2066 d are shown mating with base tab 2054 d toform non-adjacent tab group 2068 d.

FIG. 47 shows a side view of the foil layers of a capacitor stack 2024according to one embodiment where both one or more anode layers 2046 andone or more cathode layers 2044 are portioned into cathode tab groups2070 and anode tab groups 2072.

Capacitor stack 2024 comprises separators 2048 between foil layers ofalternating cathode layers 2044 and anode layers 2046. The anode layersand cathode layers form capacitive elements 2042. The cathode layersinclude a base layer 2050 and secondary layers 2052. The base layer 2050has base tabs 2054 a-2054 d and the secondary layers 2052 have matchingtabs 2058. Each matching tab 2058 overlays one of the base tabs 2054a-2054 d of the base layer 2050. The cathode layers 2044 connect to thebase layer 2050.

The anode layers 2046 include a secondary base layer 2076 with secondarybase tabs 2078 a-2078 d and additional secondary layers 2080. Each ofthe additional secondary layers 2080 has a secondary matching tab 2082with each secondary matching tab 2082 overlaying one of the secondarybase tabs 2078 a-2078 d of the secondary base layer 2076. For example,secondary matching tab 2082 c vertically matches or overlays secondarybase tab 2078 c. Each of the anode layers 2046 connect to the secondarybase layer 2076.

In one or more of the embodiments described above, the foil layers arespread out or distributed over multiple locations. For example, thecathode layers may be spread out over four locations with four tabgroups, with the thickness of each tab group at each location beingabout 0.006 inch (assuming that 5 layers at 0.00118 inch per layer areat each location). This thinness of the tab group allows the stackedunit to be placed into the housing with the tab groups occupying thespace between the housing and the edge of the stack or the clearancespace between the lid and the top of the stack. As a comparison, if thecathode tabs were all brought out at one location, the thickness wouldbe greater than 0.020 inch and make it difficult, if not practicallyimpossible, to fold the tabs collectively over the stack as in FIGS. 44and 45. Thus, this thickness would require that part of the stack beremoved or the case enlarged to allow space for routing and connectingthe cathode layer connections, thereby reducing the packing efficiencyof the capacitor.

One embodiment of a method to cut foil layers out of etched and unetchedaluminum foil using a laser is described below. In one embodiment, themethod of preparing aluminum foil layers for electrolytic capacitorsincludes cutting a capacitor foil layer out of a sheet of aluminum foilwith a laser, removing the foil layer from the sheet of aluminum foil,and inserting the foil layer shape in a capacitor. The foil layer may beused as a cathode layer or as an anode layer. In some embodiments, thefoil layer includes a plurality of tabs.

In various embodiments, the cutting may be partially through the sheet,the method may include cutting multiple sheets at one time, the methodmay include cutting multiple layers of sheets including paperseparators, and/or the method may include cutting a portion or an entirecapacitor stack at one time.

In some embodiments, the method includes laying out a pattern ofcapacitor foil layer shapes, delivering the aluminum foil to the laserin a roll, cutting different shapes out of the sheet of aluminum foil,and cutting through multiple layered sheets of aluminum foil. The methodis used to cut out the intricate shapes of a multi-leg or multi-tab foillayer.

Using the above laser cutting method has one or more of the followingadvantages: a) rapid prototyping, b) the cut out shape does not drop outof the foil until needed, making for easier handling, c) the methodeliminates the need for constant sharpening of expensive dies, d) themethod does not produce burrs or particulates. Thus, allowing the use ofthinner separators, e) the method allows for optimal pattern layout onthe foil reducing the amount of generated waste, f) the foil may bedelivered to the laser in several ways including rolls, sheets or smallpieces, and g) the laser can be set up to cut out different shapes outof the shame sheet. The method has the advantage of cutting out theintricate shapes of the multiple tab cathode described above withouttearing the closely spaced tabs. In addition, the intricate shapes canbe formed without developing an expensive die that requires sharpening.

In one embodiment, the foil is cut using a Signature 75 lasermanufactured by Control Laser Corporation. In various embodiments, thelaser was set at the following setting: current 18-23, 5-8 kHz, and aspeed of 0.35 to 1.5 inches/second.

FIG. 48 illustrates an example of a process flow for a method formanufacturing a capacitor 2018 having a capacitor stack 2024 with one ormore of the features described above. The method of FIG. 48 is anexample of one embodiment and it is understood that different steps maybe omitted, combined, and/or the order changed within the scope of oneor more embodiments of the present subject matter.

The method includes, at 2410, stacking the anode conductive layerswithin an external alignment mechanism 2408 and aligning them therein.In some embodiments, the anode stack is pressed 2412, as furtherdescribed below. The separator is aligned with the anode layers 2414,and the separator is coupled with the anode stack 2416, for example, bybonding using, for example, an adhesive. The cathode layer is alignedwith the cathode separator at 2420, and the cathode separator is coupledwith the cathode layer at 2422, for example, by bonding the cathodeseparator with the cathode layer using, for example, an adhesive.

In one embodiment, the anode stack and cathode stack are individuallypressed o improve the flatness of each stack and to reduce or eliminatewarpage, and are optionally are pressed to a specific, predeterminedheight. In another option, the capacitor stack 2024 is pressed toimprove the flatness and to reduce or eliminate warpage. In oneembodiment, the capacitor stack 2024 is pressed to a specific height toimprove the flatness and to reduce or eliminate warpage. Pressing to aspecific height helps to maintain consistency in the manufacturingprocess. Each anode stack 2100, each cathode stack 2300-2304, each layerset, the capacitor stack 2024 of all of the layer sets form, in effect,a spring. The spring rate will vary from capacitor stack 2024 tocapacitor stack 2024 due, in part, to variations in the foil suppliedand/or in the manufacturing processes associated with cutting the foilas well as the general handling of the part. Pressing the anode stack2100, the cathode stacks 2300-2304, the layer set, or the capacitorstack 2024 to a controlled height maintains consistency in the assemblyprocess in that each stack 2100, 2300-2304, layer set or capacitor stack2024 will be maintained at the same height regardless of initial springrate. Among other things, this assures a consistent fit between thecapacitor stack 2024 and the case 2020 (FIG. 18).

Referring again to FIG. 35, at 2430, the cathode, anode, and separatorlayers are stacked and aligned by the outer edges of the separatorsusing the external alignment mechanism 2400 to form a capacitor stack2024. The capacitor stack 2024 is optionally partially taped at 2432.Optionally, at 2434 the capacitor stack is clamped and annealed. Forexample, an anode stack is pressed to a specified height, and thenassembled into the capacitor stack 2024. The capacitor stack 2024 isclamped to a specified height and annealed. In one example, annealingincludes heating to a temperature of about 85 degrees C., soaking forabout 12 hours, and cooling to 23 degrees C. degrees for about 1 hour.

In another embodiment, the components are individually annealed.Annealing reduces or eliminates undesired residual stresses whichcontribute to warpage and can help to provide improved flatness of theoverall capacitor stack 2024. Annealing can also be performed after aportion of an electrode has been deformed to retain the deformed shapeand reduce effect of material relaxation. In applications where theanode conductive layers are deformed annealing after deforming can alsoreduce creation of discontinuities of the dielectric layer on thedeformed portion of an anode stack. Annealing reduces stresses,increases softness and ductility and produces a specific microstructure.A variety of annealing heat treatments can be applied to the componentsof the capacitor to accomplish the desired result.

Further processing includes welding the cathode legs 2436, taping thecapacitor stack 2438, welding the anode stack 2440, and welding thefeedthrough 2442, and finish taping the capacitor stack 2444. Inaddition, the capacitor stack is inserted into the capacitor case 2446,the case cover and the cathode ribbon are welded to the case at 2448.The feedthrough opening is sealed at 2452. The process further includesa vacuum bake and backfill at 2454, clamping the capacitor at 2456, andan aging process at 2458.

Another embodiment for stacking a capacitor stack is described below. Inone or more of the embodiments, the capacitor stack includes a curvedprofile. As used below, the term “profile” refers to the general outlineof a portion of an object taken in or projected onto a plane generallyperpendicular to a major surface of the object. Thus, for example, insome flat capacitors, profile means the outline of the capacitor caseand/or the capacitor stack taken in a plane perpendicular to the majorsurfaces of the case or the capacitor stack.

FIG. 49 shows a portion of a capacitor 3100 according to one embodiment.Capacitor 3100 includes one or more of the features of capacitor 100 ofFIG. 1. Accordingly, certain details will be omitted herein. Capacitor3100 includes a stack 3102 of two or more electrically coupled capacitormodules 3102 a, 3102 b, 3102 c, 3102 d, and 3102 e within a capacitorcase 3104. Modules 3102 a-3102 e are staggered so that their edgesgenerally (or at least a portion of side of the stack) define a profile3106 that generally conforms or is substantially congruent to anadjacent curved interior portion 3104 a of capacitor case 3104.

FIG. 50, a section view of capacitor 3100 taken along line 2-2, showsthat modules 3102 a-3102 e are staggered in two dimensions. In thisview, capacitor modules 3102 a-3102 e define a profile 3108, which isgenerally congruent to a curved portion 3104 b of case 3104. Althoughprofiles 3106 and 3108 are quite distinct in this example embodiment,other embodiments make profiles 3106 and 3108 substantially congruent.

In one embodiment, each capacitor module includes a three-layer etchedand/or perforated anode, a cathode, and at least oneelectrolyte-carrying separator between the anode and the cathode. Theanode and cathode comprise foils of aluminum, tantalum, hafnium,niobium, titanium, zirconium, or combinations of these metals.Additionally, each capacitor module is sandwiched between two pairs ofelectrolyte-carrying separators, with the separators extending beyondthe anode and cathode to prevent undesirable shorting with the case.Alternatively, separate insulative layer can be placed between thecapacitor modules and the case interior walls to prevent shorting.

In other embodiments, the capacitor modules take other forms havingdifferent numbers of anode layers and separators. For example, in someembodiments, the anodes, cathode, and separators in one or more of thecapacitor modules are staggered to define curved module faces thatconfront the interior surfaces 3104 a or 3104 b of the case. Also, insome embodiments, one or more of the anodes or cathodes are coupled tothe case, making it either anodic or cathodic.

To define the staggered edge faces and thus the curved profile, someembodiments which provide the curved profile in a single dimension, usea set of generally congruent modules of different sizes. For example,one embodiment includes four generally D-shaped modules, each with acommon width and height, but with four successively smaller lengths. Themodules are stacked, each module having at least one edge alignedvertically with the corresponding edges of adjacent modules.

FIG. 51 shows an implantable heart monitor 3300 including a monitorhousing 3310 and two capacitors 3320 and 3330. Monitor housing 3310includes two curved portions 3312 and 3314 and adjoining straightportions 3316 and 3318. Capacitor 3320 includes case 3322 and elevencapacitor modules 3324. Case 3322 includes a curved portion 3322 a and astraight portion 3322 b, respectively confronting curved portion 3312and straight portion 3316 of housing 3310.

Capacitor modules 3324 include a set of staggered modules 3324 a and aset of unstaggered modules 3324 b. The set of staggered modules 3324 aconfront curved portion 3322 a of case 3322 and have edges arranged todefine a curved profile 3326 generally congruent to the profile ofcurved portion 3322. Modules 3324 b, which are vertically aligned,confront straight portion 3322 b of case 3322.

Similarly, capacitor 3330 includes case 3332 and eleven capacitormodules 3334. Case 3332 includes curved portion 3332 a and a straightportion 3332 b, which confront respective portion 3314 and 3318 ofhousing 3310. Capacitor modules 3334 include staggered modules 3334 a,which confront curved portion 3332 a of case 3332, have front edgesarranged to define a curved profile 3336 generally congruent to theprofile of curved portion 3332 a. Modules 3334 b confront straightportion 3332 b of case 3322.

Notably, the present embodiment provides each of modules 3324 and 3334with three anodes placed between two separators and at least one cathodeplaced adjacent one of the separators. (FIG. 51 shows the separatorscross-hatched.) However, the subject matter is not limited to anyparticular module arrangement. Indeed, some embodiments of the subjectmatter use other (greater or lesser) numbers of anodes as well asmodules. Moreover, some embodiments mix modules of differentarrangements within the same capacitor case. This allows greaterflexibility in exploiting the space available in the case as well as thehousing. For more details, see FIGS. 21-25 and the accompanyingdiscussion.

Additionally, other embodiments of the subject matter constructcapacitor cases 3322 and 3332 as a single case having two adjacentcompartments with a common wall. Modules 3324 and 3334 are each placedin a respective one of compartments. The cathodes in modules 3324 andthe anodes of modules 3334 are electrically coupled to the case; anexternal anode terminal is coupled to the anodes of module 3324; and anexternal cathode terminal is coupled to the cathodes of module 3334,thereby effecting a series connection of the two capacitors using twoexternal terminals instead of the four that are conventionally provided.

This arrangement can be made by providing two (first and second)aluminum case bodies having the desired curved portions, placingcapacitor modules in the first case body, and welding a cover to thefirst case body. Other capacitor modules can then be stacked and placedin the second case body. The cover of the first case body is then put onthe opening of the second case body and welded in place. For furtherdetails, see FIGS. 106-108 which will be discussed below.

FIG. 52 shows a perspective view of a capacitor-battery assembly 3400including two stacked U-shaped capacitors 3410 and 3420 and a battery3430 nested within the capacitors. For sake of brevity, capacitor 3420,which is of substantially identical size, shape, and structure ascapacitor 3410 in this example assembly, is not described separately.Capacitor 3410 includes legs 3412 and 3414, respective middle (orintermediate) portions 3416, and terminals 3418. Legs 3412 and 3414 areparallel, and include respective curved surfaces 3412 a and 3414 a, andrespective flat end surfaces 3412 b and 3414 b.

FIG. 53, a front view of assembly 3400 without battery 3430, shows thatcurved surfaces 3412 a and 3414 b are generally congruent to each otherand to respective curved profile 3502 and 3504 defined by capacitormodules 3500. Further, it shows a housing 3510 (in phantom) having acurved or concave portions 3512 and 3514 generally congruent with orconformant to curved or convex surfaces 3412 a and 3414 a. (Someembodiments insulate and/or separate case 3606 from housing 3602.) FIG.54, a side view of assembly 3400 without battery 3430, shows that thecurved surfaces 3412 a and 3414 b are generally perpendicular to endsurfaces 3412 a and 3412 b. Middle portion 3416 is also shown as havinga curved portion 3416 a which is congruent to a curved profile 3506defined by capacitor modules 3500 and a curved portion of 3516 ofmonitor housing 3510.

FIG. 55 is a top view of assembly 3400, showing the general outline ofcapacitor modules 3500. This FIG. also shows that battery 3430 includesterminals 3432.

In one embodiment, the cathodes of the capacitor are coupled asdescribed above for FIGS. 43-47 and the accompanying discussion. Otherembodiments couple the cathodes using tabs which are connected to eachcathode layer and then coupled together. Some embodiments couple thetabs as discussed below for FIGS. 101-105 and the accompanyingdiscussion. In another embodiment, the cathodes are coupled as discussedbelow.

FIG. 56 shows an isometric cross-section view of a portion of acapacitor stack 2300 according to one embodiment. For sake of clarity,the vertical portion of stack 3200 is shown at a larger scale than thehorizontal and axial portions. Stack 3200 includes a plurality of anodes3208 a-3208 d, a plurality of cathode plates 3206 a-3206 e, andrespective separators 3207 a-3207 h located between each anode 3208a-3208 d and cathode plate 3206 a-3206 e adjacent thereto. Each cathode,anode, and separator assembly comprises a capacitor element 3220.

In this embodiment, each of the anodes has a D-shape and includes a topmajor surface, a bottom major surface, and one or more edge facesgenerally perpendicular to each of the major surfaces. In someembodiments, the anodes are circular, square, rectangular, octagonal, orother desirable shape. In the example embodiment, each anode foil isapproximately 0.004″ (0.1016 mm) thick. Other embodiments use other sizefoils.

Cathode structure 3206 includes a plurality of cathode plates 3206a-3206 e. Each plate 3206 a-3206 e is integrally connected by respectivefold areas 3304 a-3304 d. The cathode includes first major surface 3302a and an opposing major surface 3302 b.

Cathode structure 3206 is folded so that, in cross-section, it has aserpentine, z-shaped, or s-shaped profile, interweaving under and overeach anode 3208 a-3208 d. In one embodiment, the major surface of eachcathode plate 3206 a-3206 e is substantially parallel to and faces themajor surface of an adjacent cathode plate.

In one embodiment, each anode 3208 a-3208 d is sandwiched between anadjacent pair of cathode plates. The bottom major surface of each anode3208 a-3208 d confronts a major surface of a first cathode plate (with aseparator between the two surfaces), and the top major surface of eachanode 3208 a-3208 d confronts a major surface of a second cathode plate(with a separator between the two surfaces) which is adjacent to thefirst cathode plate. Each fold area 3304 a-3304 d confronts a portion ofan edge face of each anode 3208 a-3208 d. In the example embodiment,cathode structure 3206 does not include a plurality of tabs as do anodes3208 a-3208 d. Instead, the present cathode is a single, integralstructure folded over and under each anode. Thus, the cathode-to-cathodeconnection of the present flat capacitor is provided by the integralstructure of the cathode itself.

FIG. 57 shows an unfolded cathode structure 3206 in accord with oneembodiment. In this embodiment, cathode structure 3206 is laser-cut froma single aluminum sheet. One laser-cutting method is discussed above. Insome embodiments, cathode structure 3206 is cut using high-precisiondies. In various embodiments, cathode 3206 is aluminum, tantalum,hafnium, niobium, titanium, zirconium, and combinations of these metals.However, the example embodiment is not limited to any particular foilcomposition or class of foil compositions.

In one embodiment, the aluminum sheet is cut so that cathode plates 3206a-3206 g are formed. The number of plates shown in the embodiment issimply exemplary and in no way limits the present subject matter. Eachplate 3206 a-3206 g is similar to the other plates of the cathode,having a D-shape. In some embodiments, the cathode plates are circular,rectangular, square, octagonal, and other desirable symmetrical orasymmetrical shapes. In some embodiments, each plate has a differentshape than the other plates, and the assorted shapes are varied to allowfor defining an arbitrary lateral face of the capacitor stack, such asdescribed above regarding the curved profile capacitor.

In one embodiment, each plate 3206 a-3206 g is defined by one or morecut-outs. For instance, plate 3206 b is defined by an opposing pair ofcut-outs 3404 a and 3405 a. Cut-outs 3404 a and 3405 a are opposing,slit-shaped cut-outs which have fold area 3304 a between them. Fold area3304 a integrally connects cathode plate 3206 b to cathode plate 3206 awhile also providing a fold section to allow the plates to be foldedupon each other. The other plates in cathode 3206 include slit cut-outs3404 b-3404 c and 3405 b-3405 c.

Plate 3206 b also is defined by another pair of cut-outs, cut-outs 3406a and 3407 a. In one embodiment, cut-outs 3406 a and 3407 a areopposing, rounded V-shaped cut-outs which provide for the resultantD-shape when cathode 3206 is folded. In some embodiments, the cut-outshave other shapes providing for many possible flat capacitor shapes.Possible shapes, by way of example and not limitation, include circular,rectangular, square, octagonal, and other desirable shapes. Cut-outs3406 a and 3407 a have a fold area 3304 b between them. Fold area 3304 bintegrally connects cathode plate 3206 b to cathode plate 3206 c, whilealso providing a fold section to allow the plates to be folded upon eachother. The other plates of cathode 3206 also include V-shaped cut-outs3406 b-3406 c and 3407 b-3407 c, so that each cathode plate is partiallyseparated from its neighboring cathode plates by at least one cutout.

In constructing a capacitor, cathode structure 3206 is folded in analternating manner along fold areas 3304 a-3304 f so that a serpentinestructure is formed. An anode is inserted within each fold (that is,between each neighboring cathode plate). A separator is inserted betweeneach cathode plate and each anode. In one embodiment, each of theseparators has a slightly larger surface area than the surface area ofeach of cathode plates 3206 a-3206 g.

In one embodiment, the cathode structure is coupled to case 3110 by asingle tab 3401 which is integral with a single one of the cathodeplates. In one embodiment, a single one of the plurality of cathodeplates, plate 3206 a, for example, includes an integral tab 3401 forconnecting to case 3110. In other embodiments, more than one cathodeplate can include a tab 3401. In one embodiment, terminal 3112 isdirectly connected to case 3110. In some embodiments, tab 3401 iscoupled to a feedthrough wire or terminal such as terminal 3111.

In one or more embodiments, the foldable, integral cathode structuredescribed herein provides the cathode-to-cathode connections required byflat capacitors without requiring the manufacturer to attach separatetabs to each cathode. This cathode structure minimizes the space whichis required by the joints and the tabs. Furthermore, the foldablecathode structure also helps increase reliability of the capacitor sincethe stress caused by welding tabs to the cathodes is eliminated, and thenumber of interconnects is reduced.

FIG. 58 shows a flat capacitor 4100 in accord with one embodiment of thepresent subject matter. Capacitor 4100 includes one or more of thefeatures of capacitor 100 of FIG. 1. Thus the present discussion willomit some details which are referred to above regarding FIG. 1.Capacitor 4100 includes a case 4101, a feedthrough assembly 4103, aterminal 4104, and a sealing member 4105.

Case 4101 includes a feedthrough hole 4107 which is drilled, molded, orpunched in a portion of a wall of case 4101. Feedthrough hole 4107 is inpart defined by an edge 4107 a which outlines the feedthrough holewithin case 4101. Feedthrough hole 4107 provides a passage forconnecting feedthrough assembly 4103 to circuitry outside of case 4101.In some embodiments, case 4101 includes two or more feedthrough holesfor providing a second or third feedthrough assembly.

Feedthrough assembly 4103 and terminal 4104 connect capacitor elementsto outside circuitry. In the example embodiment, feedthrough assembly4103 extends through feedthrough hole 4107 and is insulated from case4101. Terminal 4104 is directly connected to case 4101. Alternatively,in some embodiments, the capacitor incorporates other connectionmethods, depending on other design factors. In various embodiments, twoor more insulated feedthrough assemblies are employed.

In one embodiment, sealing member 4105, such as an epoxy, is depositedaround feedthrough hole 4107 and feedthrough assembly 4103 to insulatefeedthrough assembly 4103 from case 4101 and to seal an electrolytewithin the case. An example epoxy is a two-part epoxy manufactured byDexter Hysol. This includes a casting resin compound (manufacturer No.EE 4183), a casting compound (manufacturer No. EE 4215), and a hardener(manufacturer No. HD 3404). The example two-part epoxy is mixed in aratio of hardener=0.055*casting resin. The mixture is cured at 0.5 hoursat 60 degrees Celsius or 1.5 hours at room temperature. Another epoxy isa UV cure epoxy such as manufactured by Dymax, Inc., which can be curedusing an Acticure (manufactured by GenTec) ultraviolet curing system at7 W/cm2 at a distance of 0.25″ for approximately 10 seconds. In oneembodiment, sealing member 4105 is a plug, as will be discussed below.

In one embodiment, the sealing member provides a non-hermetic seal. Inone embodiment, the sealing member includes an elastic plug which willbe discussed in further detail below.

FIGS. 59 and 60 show exploded views of capacitor 4100. Capacitor 4100includes a capacitor stack 4202 mounted within an internal cavity 4212.The example capacitor stack 4202 includes a plurality of capacitormodules or elements 4205 a, 4205 b, 4205 c, . . . , 4205 n. Each ofelements 4205 a-4205 n includes a cathode, an anode, and a separatorbetween the cathode and the anode.

In one embodiment, each cathode of capacitor stack 4202 is connected tothe other cathodes and to conductive case 4101. Terminal 4104 isattached to case 4101 to provide a cathode connection to outsidecircuitry. In some embodiments, the cathode is coupled to a feedthroughconductor extending through a feedthrough hole.

In one embodiment, each anode is connected to the other anodes of thecapacitor. Attached to the anode of each capacitor element 4205 a-4205 nis a conductive tab or connection member 4201, as discussed above. Inone embodiment, each connection member 4201 includes an edge face 4215which is substantially perpendicular to the major surface of the anodes.Edge face 4215 provides a conductive surface for connecting eachcapacitor element 4205 a-4205 n to feedthrough assembly 4103. The anodeconnection members 4201 are welded or crimped together and are coupledto feedthrough assembly 4103 for electrically connecting the anode tocircuitry outside the case. In some embodiments, the cathode is coupledto a feedthrough assembly and the anode is connected to the case. Inother embodiments, both the anode and the cathode are connected tofeedthroughs.

In one embodiment, connection members 4201 are edge-welded to each otheras discussed above. Edge-welding the connection members provides a flatconnection surface 4216, which includes one or more edge faces 4215 ofconnection members 4201. In some embodiments, connection members 4201are crimped, soldered, and/or connected by an electrically conductiveadhesive.

In one embodiment, feedthrough assembly 4103 includes two members, afeedthrough wire or conductor 4203 and a coupling member 4204. Couplingmember 4204 is attached to capacitor stack 4202 at connection surface4216, and feedthrough conductor 4203 is attached to coupling member4204. In one embodiment, coupling member 4204 partially extends throughfeedthrough hole 4107.

Feedthrough conductor 4203 is a conductive member which can includematerial such as nickel, gold plated nickel, platinum, aluminum, orother conductive metal. Feedthrough conductor 4203 has a proximal endportion 4217 attached to coupling member 4204 and a distal end portion4218 for attaching to circuitry outside the case, such as defibrillatoror cardioverter circuitry. In one embodiment, feedthrough conductor 4203has a diameter of approximately 0.016″ (0.4064 mm). However, otherembodiments have feedthrough conductors of different diameters and/ornon-circular cross-sections.

FIG. 61 shows a cross-sectional side view of details of one embodimentof feedthrough assembly 4103 and its connection to connection members4201. As discussed above, in one embodiment, the edge faces 4215 of eachconnection member 4201 form a substantially flat connection surface 4216and coupling member 4204 is directly attached to connection members 4201at surface 4216.

In one embodiment, coupling member 4204 is a high-purity aluminum memberwhich is able to withstand the high voltages generated within thecapacitor case. In other embodiments it is made from another conductivematerial compatible with the capacitor stack. Coupling member 4204includes a base 4404 and a holding tube 4407. On one side of base 4404is a planar surface 4405 for attaching to the planar surface 4216presented by edge-welded connection members 4201.

FIG. 63 shows additional details of example base 4404. In the exampleembodiment, base 4404 is substantially rectangular having a pair ofopposing rounded or curved ends 4602 and 4604.

Referring again to FIG. 61, in one embodiment, coupling member 4204 issituated so that surface 4405 abuts connection member surface 4216.Coupling member 4204 is laser welded using a butt-weld to surface 4216of connection members 4201. Alternatively, coupling member 4204 isattached using other means. Butt-welding coupling member 4204 directlyto connection members 4201 provides an optimal electrical connectionbetween capacitor stack 4202 and the feedthrough assembly. Moreover, italso provides for a compact capacitor since very little, if any, spaceis wasted between capacitor stack 4202 and feedthrough assembly 4103.Also, since coupling member 4204 is directly attached to capacitor stack4202, it helps support feedthrough conductor 4203 while a sealing member4105, such as an epoxy, is applied to the feedthrough hole area.

Holding tube 4407 is located on the opposing side of base 4404 fromsurface 4405. Tube 4407 is a cylindrical member having an outer diameterdimensioned to fit within feedthrough hole 4107. Tube 4407 has amounting section such as mounting hole 4401 defined in part by an innersurface 4402 of holding tube 4406 which is generally perpendicular tobase surface 4405. Hole 4401 is located down an axial portion of thetube.

Mounting section or hole 4401 is for receiving proximal end portion 4217of feedthrough conductor 4203. The surface of feedthrough conductor 4203contacts inner surface 4402. In one embodiment, hole 4401 isapproximately 0.016″ (0.4064 mm) in diameter. Alternatively, itsdiameter can conform with the size of conductor 4203 so that feedthroughconductor 4203 can matably fit within the hole. In one embodiment,coupling member 4204 has a height 204 h of approximately 0.085″ (2.519mm). Other embodiments range from 0.050″ to 0.100″ or higher. Someembodiments provide a height of greater than 0.100″.

FIGS. 62A and 62B show an attachment of feedthrough conductor 4203 tocoupling member 4204 according to one embodiment. In the presentembodiment, feedthrough conductor 4203 and coupling member 4204 areconnected at a crimp 4502. Alternatively, they are welded, soldered,glued or interference fit together, as will be discussed below. Examplecrimp 4502 compresses inner surface 4402 (see FIG. 61) of tube 4407 intomechanical and electrical connection with the surface of portions offeedthrough conductor 4203. In one embodiment, a double crimp isemployed. In some embodiments, a single crimp, double crimp, triplecrimp or more are used.

In one embodiment, inner surface 4402 of coupling member 4204 is acurved surface, defining an annular connection member. Crimp 4502compresses and deforms opposing surfaces of annular inner surface 4402to contact conductor 4203. In one embodiment, the opposing surfaces ofinner surface 4402 are separated by a first distance prior to beingcrimped and separated by a second distance, smaller than the firstdistance, after being crimped.

FIG. 64 shows another example coupling member 4700. Member 4700 includesa base 4701 and a holding tube 4702. Base 4701 is a circular-shapedbase. In one embodiment, base 4701 has a diameter of approximately0.050″ (1.27 mm). In one embodiment (not shown), the base is squareshaped.

FIG. 65A shows another example of a coupling member 4800. Member 4800does not include a base. In one embodiment, hole 4401 runs completelythrough holding tube 4802. In one embodiment, one end of tube 4802 has aconnection surface and is attached to surface 4216 of connection members4201. A second end of tube 4802 receives feedthrough conductor 4203.

FIG. 65B shows another example of a coupling member 4850. Member 4850does not include a base. In one embodiment, hole 4401 runs onlypartially through a holding tube 4852. In one embodiment, one end ofmember 4850 has a connection surface and is attached to surface 4216 ofconnection members 4201. An end of tube 4802 receives feedthroughconductor 4203.

FIG. 66 shows a side view of feedthrough assembly 4103 in whichfeedthrough conductor 4203 is coupled to coupling member 4204 at one ormore arc percussion welding areas, such as areas 4982 a and 4982 b. Anexample arc percussion welding machine is manufactured by Morrow TechIndustries of Broomfield, Colo. In this embodiment, the conductor 4203and coupling members are not crimped together. However, some embodimentsinclude both welding and crimping.

FIG. 67 shows an exploded view of capacitor 4100 having a sealing membersuch as a plug 4106 according to one embodiment of the present subjectmatter. Plug 4106 is insertable into feedthrough hole 4107 of case 4101.In one embodiment, plug 4106 has an outer diameter which is larger thanthe diameter of feedthrough hole 4107, and the manufacturer inserts itwithin hole 4107 in an interference fit. When plug 4106 is locatedwithin feedthrough hole 4107, the plug seals feedthrough hole 4107 andelectrically insulates feedthrough assembly 4103 from case 4101. In someembodiments plug 4106 includes one or more flanges, which will bediscussed below.

FIG. 68 shows a cross-sectional view of plug 4106 assembled withcapacitor case 4101. The present example show coupling member 4204attached to capacitor stack 4202. However, in other embodiments plug4106 can also be used in capacitors having other types of feedthroughassemblies. In one embodiment, plug 4106 electrically insulates case4101 from coupling member 4204. Coupling member 4204 has a first end4115 located in the interior of case 4101 and coupled to capacitor stack4202. Coupling member 4204 also includes a second end 4111 locatedexterior to case 4101 for connecting to circuitry, such asdefibrillator, or other implantable medical device circuitry. In oneembodiment, coupling member 4204 has a feedthrough terminal attachedthereto.

In this embodiment, plug 4106 is a double-flanged plug. Plug 4106includes a first flange 4108. First flange 4108 includes a first surface4108 a which faces the inner surface of case 4101. When the capacitorbegins to become pressurized, pressure against a second surface 4108 bforces first surface 4108 a against the case. Thus, flange 4108 createsa seal against the inner surface of case 4101.

In this embodiment, plug 4106 includes a second flange 4109. Flange 4109includes a surface which faces the outer surface of case 4101.

Plug 4106 also includes a plug portion 4110 which is located between anddefined by first flange 4108 and second flange 4109. Portion 4110 has asmaller diameter than either flange 4108 and/or 4109. Case edge 4107 aconfronts plug 4106 at portion 4110. In this embodiment, portion 4110has a normal, unstressed outer diameter approximately equal to thediameter of feedthrough hole 4107. In some embodiments, the unstressedouter diameter is larger than the diameter of feedthrough hole 4107. Insome embodiments, the unstressed outer diameter is smaller than hole4107. As one example, in this embodiment flange 4108 has a diameter ofapproximately 0.080 inches and portion 4110 has a diameter ofapproximately 0.060 inches.

Plug 4106 also includes a central passage or hole 4102. In oneembodiment, hole 4102 is axially located through the center of plug 4106and has an unstressed diameter 4102 d which is smaller than or equal toa diameter 4103 d of a portion of feedthrough member 4103 which ismounted within hole 4102. In various embodiments, diameter 4102 d mayrange from approximately 0.015 inches to approximately 0.033 inches. Inother embodiments, diameter 4102 d is smaller than 0.015 inches. In someembodiments it is greater than 0.033 inches. Other embodiments vary thehole size depending on the size of the feedthrough conductor used. Insome embodiments, when a feedthrough member such as coupling member 4204is inserted through hole 4102, an interference fit seal is developedbetween the feedthrough member and the plug. In other embodiments,hydrogen gas can escape along the feedthrough member/plug 4106 border.

In one embodiment, plug 4106 is made from a compressible, elasticmaterial such as rubber, plastic, thermoplastic, or other elastic orelastomeric material. In one embodiment, when plug 4106 is mountedwithin feedthrough hole 4107 and feedthrough member 4103 is mountedwithin hole 4102, plug portion 4110 is compressed between assembly 4103and edge 4107 a of feedthrough hole 4107 and the plug exerts a radialforce on edge 4107 a of the feedthrough hole. This forces or compressesplug 4106 into an interference or compression fit between feedthroughhole edge 4107 a and member 4204, thus helping to seal electrolytesolution within case 4101. In other embodiments, the diameter of portion4110 is smaller than hole 4107 and an interference fit betweenfeedthrough hole edge 4107 a and member 4204 is not created.

In one embodiment, as noted above, flange 4108 provides a sealing meansfor helping seal electrolyte within the case. Accordingly, in someembodiments, when the diameter of portion 4110 is smaller than hole 4107and an interference fit between feedthrough hole edge 4107 a and member4204 is not created, only flange 4108 provides a sealing means betweencase 4101 and plug 4106. Advantageously, the seal or seals are formedautomatically. Thus, in one embodiment, assembling and tightening ascrew or other extraneous hardware is not required to seal thecapacitor.

In one embodiment, second flange 4109 provides support for mounting plug4106 within hole 4107. For instance, when plug 4106 is mounted in hole4107, flanges 4108 and 4109 each help hold plug 4106 in place once it ismounted, but before the coupling member 4204 is inserted through hole4102. This aides the manufacturing process.

In one embodiment second flange 4109 includes a tapered section whereinan outer portion 4109 a of flange 4109 has a smaller diameter than aninner portion 4109 b. The tapered shape of flange 4109 aids in insertingplug 4106 into hole 4107. Some embodiments omit the tapered shape andflange 4109 has a uniform outer diameter. Other embodiments provide atapered shape for first flange 4108. Other embodiments provide taperedsections on both flanges.

In this embodiment, flange 4108 has a larger diameter than flange 4109.In some embodiments, the two flanges have substantially equal diameters.In further embodiments, flange 4109 has a larger diameter than flange4108.

Some embodiments omit either or both of flanges 4108 and 4109. Forinstance, in some embodiments plug 4106 has a generally cylindricalshape. In other embodiments, plug 4106 has an hour-glass shape or othershape which closely fits within feedthrough hole 4107. In someembodiments, plug 4106 is a mass of elastic material with a dimensionapproximately equal to or larger than the width of feedthrough hole4107.

In one embodiment, plug 4106 seals the electrolyte within capacitor case4101, but it does not provide a hermetic seal. Hydrogen is createdduring consumption of water from the electrolyte and continues to beformed throughout the life of the capacitor. This can cause ahermetically sealed capacitor case to bulge outward from the hydrogengas production within, thus risking long-term device reliability due toshorting.

Accordingly, in one embodiment plug 4106 permits out-gassing of hydrogengas, thus alleviating any problems. For instance, in one embodiment,flange 4108 creates a seal to the inner wall of the case 4101. A pathwayfor the gas to escape is then present along the border between couplingmember 4204 and plug 4106.

FIG. 69 shows a cross-sectional side view of a plug 4120 according toone embodiment. Plug 4120 includes one or more features of plug 4106 anddiscussion of unnecessary details will be omitted. Plug 4120 includes afirst flange 4128, a second flange 4129, and a portion 4130 between thetwo flanges 4128 and 4129. In one embodiment, plug 4130 includes a hole4132. Hole 4132 has a sealing section such as a narrow section 4132 b,which is located between two nominal diameter sections 4132 a and 4132b. Other embodiments omit section 4132 b or move it to either end,thereby omitting sections 4132 a or 4132 b.

In one embodiment, narrow section 4132 b provides an O-ring typeinterference fit for a feedthrough member such as coupling member 4204.In this embodiment, narrow section 4132 b is generally located withinsecond flange 4129. Other embodiments locate the narrow section withincentral portion 4130. Other embodiments locate the narrow section withinfirst flange 4128. By way of example, in one embodiment, the nominaldiameters of sections 4132 a and 4132 c is approximately 0.032 inches,and the diameter of narrow section 4132 b is 0.026 inches.

Referring again to FIG. 67, one method of assembling a capacitor havinga plug 4106 is as follows. Plug 4106 is inserted into feedthrough hole4107 of case 4101. In one embodiment, plug 4106 includes a double-flangeconstruction which helps hold the plug in place once it is mounted.Feedthrough assembly 4103 is attached to capacitor stack 4202 andinserted through inner hole 4102 of plug 4106 while capacitor stack 4202is placed within the cavity of case 4101. An interference fit betweenplug 4106 and feedthrough 4103 and between case 4101 and plug 4106 arecreated. Thus, a seal is formed between the interior of case 4101 andthe exterior of case 4101.

FIG. 70 shows a feedthrough assembly according to another embodiment ofthe present subject matter. FIG. 70 shows an exploded view of a flatcapacitor 5100 incorporating a feedthrough assembly 5101. Although thepresent embodiment is described as a flat capacitor, other capacitorforms can take advantage of the feedthrough assembly and the otherfeatures discussed in the present description.

Capacitor 5100 includes one or more features of capacitor 100 of FIG. 1and details will be omitted for the sake of clarity. In the presentembodiment, capacitor 5100 includes a feedthrough assembly 5101, aconductor 5102, one or more capacitor element tabs 5104, a capacitorstack 5105, a terminal 5112, and a capacitor housing or case 5113. Case5113 includes a container portion 5110 and a lid 5109. Container portion5110 has a cavity for holding capacitor stack 5105. The cavity isdefined in part by a bottom side 5115 surrounded by a side wall 5114.When lid 5109 is attached to the container portion of the case, the lidand the bottom side are substantially parallel to each other.

In one embodiment, case 5113 includes a feedthrough port or hole 5111.Alternatively, the case can include one, two, three, four or more holes,depending on other design factors which will be discussed below.

Capacitor stack 5105 is situated within capacitor case 5113. In theexample embodiment, capacitor stack 5105 includes one or more capacitormodules or elements 5120 a, 5120 b, . . . , 5120 n. The number ofcapacitor elements 5120 can vary according to capacitive need and sizeof a capacitor desired. Each capacitor element 5120 a-5120 n includes acathode 5106, an anode 5108, and a separator 5107 sandwiched betweencathode 5106 and anode 5108. In some embodiments, other numbers andarrangements of anodes, cathodes, and separators are used.

In one embodiment, attached to each capacitive element 5120 a-5120 n isa foil connection structure such as a conductive tab 5104, made fromaluminum or other suitable material, which electrically connects eachanode to the other anodes of capacitor stack 5105. Each tab 5104 of eachcapacitor element 5120 a-5120 n is connected to each other tab 5104 andcoupled to conductor 5102 for electrically coupling the anode to acomponent outside the case.

In one embodiment, conductor 5102 is an aluminum ribbon tab and iscoupled at one end to anode tabs 5104 and at another end to feedthroughassembly 5101 for electrically coupling capacitor stack 5105 to acomponent outside the case through hole 5111. Conductor 5102 is coupledto feedthrough assembly 5101 by welding or other coupling means.

In one embodiment, each cathode 5106 is a foil attached to the othercathodes of capacitor stack 5105. In the present embodiment, thecathodes are attached to case 5113. Terminal 5112 is attached to case5113. In some embodiments, each cathode 5106 is joined to the othercathodes at cathode tabs for providing an external cathode connection.In one embodiment, cathodes 5106 are coupled to a feedthrough assemblyextending through a feedthrough hole, such as hole 5111. In variousembodiments, the anode is connected to the case and the cathode isconnected to a feedthrough assembly, or both anodes and cathodes areconnected to feedthrough assemblies.

FIG. 71 shows a larger view of feedthrough assembly 5101. Feedthroughassembly 5101 includes an inner core or central feedthrough member 5201for electrically connecting conductor 5102 to an outside component. Inone embodiment, central or inner member 5201 is an annular member whichcomprises a conductive material, such as aluminum, and has a bore orpassage 5204 extending through it. In one embodiment, passage 5204extends all the way through feedthrough member 5201. In someembodiments, passage 5204 extends partially through the member.

Feedthrough assembly 5101 also includes an outer member 5202 molded,glued, or otherwise located around central member 5201. In oneembodiment, outer member 5202 is an electrically insulating material,such as a plastic or thermoplastic, for insulating the central member5201 from case 5113. Member 5202 is an annular, flanged member having acylindrical stepped-shaped structure. In one embodiment, outer member5202 includes a substantially flat surface 5205 and a second surface5207 substantially perpendicular to surface 5205.

FIG. 72 shows a partial cross-section view of capacitor 5100 connectedby feedthrough assembly 5101 to a component, such as heart monitorcircuitry 5308. In the present embodiment, outer member 5202 is attachedto case 5113 by an epoxy or other adhesive method at areas 5309 and5310. Some embodiments include threads on surface 5207 and/or formmember 5202 from an elastic material that is compressed within hole5111. In some embodiments, the elastic material is permeable to allowpassage of fluids such as hydrogen gas to escape from case 5113. Outermember surface 5205 abuts an inner surface of case 5113 aroundfeedthrough hole 5111 and surface 5207 abuts or confronts an edgesurface of the feedthrough hole.

Tabs 5104 are connected to one end of conductor 5102. In variousembodiments, conductor 5102 is welded, crimped, or otherwise attached tothe tabs. A second end of conductor 102 is welded or crimped orotherwise attached to a substantially flat surface 5307 of conductivecentral member 5201. In one embodiment, conductor 5102 is folded overitself between tabs 5104 and feedthrough assembly 5101. In someembodiments, the fold is omitted to reduce the space between tabs 5104and feedthrough assembly 5101. In one embodiment, conductor 5102 isomitted and central member 5201 is directly attached to tabs 5104.

Central member 5201 electrically connects conductor 5102 to outsidecomponent 5308. In the example embodiment, central member 5201 is acylindrical stepped-shaped member having a first annular section and asecond annular flange section. Member 5201 has a first end 5320 withincase 5113 and a second end 5330 extending through hole 5111. In oneembodiment, second end 5330 has a substantially flat end surface whichis positioned flush with an outer surface of case 5113. In otherembodiments, second end 5330 is partially within feedthrough hole 5111.In some embodiments, second end 5330 protrudes from hole 5111 andextends a distance from case 5113.

In one embodiment, central member passage 5204 includes a mountingsection 5311, such as a threaded section. A feedthrough terminalfastener 5304 includes a mounting section (in one embodiment, a threadedsection) that corresponds to mounting section 5311 of passage 5204 sothat feedthrough terminal fastener 5304 is removably attachable to thecentral member of feedthrough assembly 5101. In some embodiments, asealant such as Loctite is placed on the mounting section to provide fora sealed connection.

Terminal fastener 5304 attaches a feedthrough terminal 5303 tofeedthrough assembly 5101. Terminal 5303 in turn is attached (forexample, soldered or welded) to a connector 5302 which is connected tocomponent 5308. In one embodiment, terminal 5303 is a conductivematerial, such as aluminum or gold-plated nickel. Other embodiments haveother suitable conductive materials. Since terminal fastener 5304 isremovable, it allows a defective capacitor to be replaced by a good one.

For instance, if capacitor 5100 were installed in a defibrillator and itwas discovered that the capacitor was defective, a user could disengagefeedthrough terminal 5303 from the capacitor and mount a new capacitorin place of the defective one. This is in contrast with conventionalfeedthrough assemblies in which one would have to cut connector 5302from terminal 5303 and then reweld or re-solder the connector to a newcapacitor. Moreover, the conventional design requires an extra lengthfor connector 5302 to allow for replacement. This extra length takes upextra space within the device, for example an implantable defibrillatoror cardioverter, including the capacitor. Thus, the example embodimentpermits an optimal, minimal length of connector 5302 while stillpermitting a defective capacitor to be replaced without having to throwthe whole device away.

In one embodiment, conductor 5102 includes one or more holes, such as ahole 5301, adjacent to and contiguous with passage 5204. In someembodiments, hole 5301 is as small as a pinhole. In the presentembodiment, hole 5301 is aligned with passage 5204 and provides acontinuous passage that effectively extends passage 5204 into theinterior of case 5113, allowing introduction of an electrolyte solution(or other material) into case 5113 through passage 5204 and hole 5301.Thus, a user can fill case 5113 with electrolyte through an existingfeedthrough hole instead of providing and sealing a separate backfillhole. Thus, the present embodiment saves at least one manufacturingstep. In some embodiments, conductor 5102 is attached to feedthroughassembly 5101 so that it is slightly offset from passage 5204, thusproviding a continuous passage into the interior of case 5113. In someembodiments, conductor 5102 includes two, three, or more holes.

FIG. 73 shows a partial cross-section view of a feedthrough assembly5400 according to another embodiment. Feedthrough assembly 5400 includesa central feedthrough member 5402 and an outer member 5401. In oneembodiment, member 5402 is a cylindrical, step-shaped member made from aconductive material such as aluminum. Central member 5401 has a passage5403 extending through it. Conductor 5102 is attached to member 5402 andincludes one or more holes 5301 adjacent to and contiguous with passage5403 so that an electrolyte solution can be deposited within case 5113through the passage 5403 and the hole 5301.

In this embodiment, passage 5403 is a non-threaded cylindrical passageadapted to have a terminal fastener (not shown) riveted, interferencefitted, glued, or otherwise coupled to it. In one embodiment, aconnector from an outside component is directly coupled within passage5403 by an interference or friction fit. In some embodiments, passage5403 has a square, triangle, or other shape for receiving a terminalfastener.

FIG. 74 shows a partial cross-section view of a feedthrough assembly5500 according to another embodiment. Feedthrough assembly 5500 includesa central feedthrough member 5501 and an outer member 5502. In oneembodiment, member 5501 is a cylindrical, step-shaped member made from aconductive material such as aluminum. Outer member 5502 is anelectrically insulative material, molded, glued, or otherwise placedaround conductive central member 5501 to electrically insulate member5501 from a conductive capacitor case.

In this embodiment, feedthrough member 5501 includes a passage 5503.Passage 5503 extends partially through a central axial portion of thecentral member. In the example embodiment, passage 5503 is threaded.This provides a mounting portion for removably mounting a threadedmember such as a terminal fastener. In some embodiments, passage 5503 isnot threaded and a terminal fastener or a terminal is interferencefitted, glued or otherwise attached within passage 5503.

FIG. 75 shows an example of a method 5700 for manufacturing anelectrolytic capacitor according to one embodiment of the presentsubject matter. Method 5700 will be discussed in reference to examplecapacitor 5100 of FIGS. 70-72. However, it is understood that the methodcan be performed on different types of capacitors. In block 5702, method5700 includes providing a capacitor case 5113 having a hole 5111. Inblock 5704, the method includes installing feedthrough assembly 5101 atleast partially into hole 5111. The feedthrough assembly 5101 includesconductive member 5201 having passage 5204 therethrough. In block 5706,method 5700 includes filling case 5113 with an electrolyte solutionthrough passage 5204. In block 5708, method 5700 includes installingterminal fastener 5304 in passage 5204. The example method saves atleast one manufacturing step since the electrolyte is filled through anexisting feedthrough hole instead of providing and sealing a separatebackfill hole.

FIG. 76 shows an example method 5800 for replacing a first capacitorinstalled in a medical device with a second capacitor. Again, the methodwill be discussed in reference to capacitor 5100. In block 5802, themethod includes disengaging a terminal 5303 coupled to a medical device5308 from a feedthrough passage 5204 of the first capacitor 5100. Inblock 5804, the method includes installing the same terminal 5303 into afeedthrough passage of the second capacitor (not shown). This providesthat the capacitor can be replaced instead of having to throw the wholeunit away.

FIG. 77 shows a method 5900 for manufacturing an implantabledefibrillator according to one embodiment of the present subject matter.Again, the method will be discussed in reference to capacitor 5100. Inblock 5902, the method includes providing a defibrillator case havingcircuitry 5308. In block 5904, the method includes providing a capacitorcase 5113 having a hole 5111. In block 5906, the method includesinstalling feedthrough assembly 5101 at least partially into hole 5111.In the example method, the feedthrough assembly 5101 includes aconductive member 5201 having a passage 5204. In block 5908, the methodincludes mounting terminal 5303 to passage 5204 using a terminalfastener 5304. In block 5910, the method includes coupling a conductor5302 coupled to defibrillator circuitry 5308 to terminal 5303.

FIGS. 78-82 show one or more embodiments for coupling a cathode or anodestack to a capacitor case.

FIG. 78 shows a perspective view of a capacitor 5018. Capacitor 5018includes one or more features described above for capacitor 100 ofFIG. 1. Accordingly, certain details will be omitted herein. Capacitor5018 includes a capacitor container 5020 including a case 5022 and alid, or cover 5024 overlying case 5022 for placement on an upper rim5026 of case 5022. A capacitor stack 5028 with a top surface 5030 isenclosed by container 5020 which defines a chamber 5032.

Capacitor stack 5028 includes a plurality of cathode and anode foillayers separated by one or more separators. The anode foil layers areconnected together and coupled to a feedthrough conductor 5034. In oneembodiment, feedthrough conductor 5034 passes through a hole in case5022, and conductor 5034 is electrically isolated from case 5022.

The cathode foil layers of stack 5028 are connected together andconnected to a conductor 5036. In one embodiment, cathode conductor 5036is a tab strip which is integral to one of the cathode layers. In otherembodiments, cathode conductor 5036 is a strip of aluminum tab stockconnected to one or more of the cathode foil layers. Cathode conductor5036 provides an electrical connection between the cathode layers andcase 5022.

FIG. 79 shows a capacitive element 5038 in accord with one embodiment.Capacitor stack 5028 includes a plurality of generally flat capacitiveelements 5038. Capacitive element 5038 includes foil layers such ascathode layer 5040 and anode layers 5042 each of whose electricalelements are connected in parallel. In this embodiment, anode layers5042 form a triple anode structure. Other embodiments include single,double, triple, four, and/or more anode foils.

FIGS. 80-82 show a partial cutaway view of capacitor 5018 duringrespective manufacturing stages in accord with one or more embodimentsof the present subject matter. Capacitor stack 5028 includes top surface5030 and a lateral face 5046 and includes one or more parallel connectedcapacitive elements, such as capacitive element 5038 shown on FIG. 79.As discussed above, in one embodiment, the anodes of each capacitiveelement have respective tabs connected together and welded at their freeends. The welded tabs are then welded (or otherwise fastened orattached) to feedthrough conductor 5034 that passes through case 5022.(See FIG. 78). In some embodiments, an unetched, integral portion ofeach of one or more anodes is used to weld or attach the anode layers toone another.

In one embodiment, cathode tabs are attached or fastened to cathodeconductor 5036. As noted above, in some embodiments cathode conductor5036 is an integral extension of a cathode foil layer, meaning forexample, that the cathode conductor and cathode foil layer are formedfrom a single piece of foil.

In one embodiment, cathode conductor 5036 extends from capacitor stack5028 and is positioned and pinched between upper rim 5026 of case 5022and cover 5024. Cover 5024 and case 5022 form an interface or seam 5048at upper rim 5026. Cathode conductor 5036 is positioned in interface5048 between case 5022 and cover 5024. Cathode conductor 5036 is pinchedbetween case 5022 and cover 5024 defining an inner conductor portion5050 and an outer conductor portion 5052. As shown in FIG. 81, in oneembodiment, at least a portion of the outer conductor portion 5052 istrimmed off of the cathode conductor 5036.

In some embodiments, cathode conductor 5036 is welded into place duringthe base/cover welding process, providing a mechanical and electricalconnection to the case 5022 without a separate connection procedure. Incontrast, if the cathode conductor is connected to the case in aseparate procedure, the extra connection requires that part of thecapacitor stack be removed or the case be enlarged to allow space forrouting and connecting the conductors, thereby reducing the packagingefficiency of the capacitor. The reduced packaging efficiency ultimatelyresults in a larger capacitor. In some embodiments, conductor 5036 iswelded or otherwise fastened to the interior or exterior of cover 5024or to the exterior of case 5022.

FIG. 82 shows a partial cutaway view of capacitor 5018 with cover 5024welded to case 5022. Cathode conductor 5036 is positioned between case5022 and cover 5024 at upper rim 5026. Cathode conductor 5036 is weldedin the interface 5048 between cover 5024 and case 5022, providing amechanical and electrical connection to the container 5020. The weldedconductor 5036, cover 5024 and case 5022 are welded together with asingle bead 5054. In one embodiment, the bead forms a hermetic sealbetween the cover 5024 and case 5022.

Among other advantages, one or more of the embodiments described aboveprovide a capacitor structure which reduces the space required forconnecting and routing the cathode conductor and thus allows a reductionin the size of the capacitor, or alternatively an increase in its energystorage capacity.

The embodiments described above show the cathode conductor electricallyconnected to the housing forming a cathodic housing. Alternativeembodiments include positioning the anode conductor between the coverand case thereby connecting the anode layers and anode conductor to thehousing forming an anodic housing.

An example embodiment of a method to connect a cathode conductor to acapacitor housing is described below. The cathode conductor is connectedto the housing by positioning the conductor between the case and thecover; positioning the cover on the case; and attaching the cover to thecase so that the conductor is electrically and mechanically connected tothe housing. In addition, other embodiments include positioning theconductor between the case and the cover at the upper rim and attachingthe cover to the case at the upper rim. In one embodiment, the case andthe cover form an interface and the positioning of the conductor betweenthe case and the cover is in the interface. In another embodiment, theattaching the cover to the case comprises welding or soldering the coverto the case. The cathode conductor is welded into place using a singlebead during the welding of the cover to the case, eliminating a separatestep of connecting the cathode conductor to the case.

One example method of providing internal interconnections and/orexternal connections is described as follows. FIG. 83A shows a top viewof a foil connection according to one embodiment. In this embodiment, awire connector 5260 is attached to a major surface of an anode layer5110 along a portion of the wire connector's length. In one embodiment,wire connectors are similarly connected to the cathode layers of thecapacitor stack. In one embodiment, wire connector 5250 is made of highpurity aluminum, is a round wire and includes a diameter allowing thedesired amount of bending and twisting as the connectors is routedthrough the capacitor case.

FIG. 83B shows a capacitor in accordance with one embodiment in whichone or more round wire connectors 5250 are connected to the cathodelayers 5120 and wire connectors 5260 are connected to anode layers 5110.The wire connectors may be made of high purity aluminum and are staked(or otherwise attached such as by welding, brazing, etc.) to theindividual cathode and anode layers.

Wire connector 5250 and 5260 connect like types of layers together andcan be used to connect the layers to external terminals. In the FIG.,the wires connected to the anode layers exit the layers at one commonlocation while the cathode layer wires exit together at a differentlocation. The anode layer wires 5260 and cathode layer wires 5250 arethen gathered into corresponding wire bundles 5261 and 5251,respectively. The bundles can then be twisted together into a cable thatcan be laid in any direction to be routed through feedthroughs 5280 toterminal connections. In the FIG., the anode layers 5110 areelectrically connected to positive terminal 5160, and the cathode layersare electrically connected to negative terminal 5150. By directlyconnecting the round wire connectors to the capacitor layers, there isno need for tabs that add to the space requirements of the capacitorcase.

In one embodiment, wire connectors 5250 and/or 5260 are insulated withthe insulation removed at the point of bundling in order to electricallyconnect like types of layers together. In another embodiment, the wiresare uninsulated and routed through the case via an insulated feedthroughhole.

Advantageously, in one or more embodiments, the cathode and anode wirescan be gathered into bundles and twisted into a cable that can be routedin any direction through a feedthrough of the capacitor case. Thisallows greater space efficiency and a smaller case for the capacitor.

Referring to FIG. 1, in one embodiment, terminal 104 is attached to case101 along a side portion of the case. FIG. 84 shows capacitor 5018having a terminal connection 5030 in accord with another embodiment. Inthis embodiment, feedthrough conductor 5034 is attached to the anodelayers inside the case as described above. The cathode layers areconnected to the case in this embodiment, and terminal connector 5030 isattached to the case in an end-on fashion by welding or brazing the endof the wire to the capacitor case.

In one embodiment, terminal connector 5030 includes a body having an endsurface which is substantially perpendicular to the body. The endsurface is positioned so that the end surface is flushly positionedagainst the surface of the case and is butt-welded to the case, whereinterminal connector is only attached to the case at its end surface andnot along any portions of its body.

In one embodiment, an expanded end 5040 at the end of the wire isprovided. The expanded end 5040 in this embodiment is in the shape of anailhead with a flat surface for attaching to the case. The surface areaof the expanded end is sufficient to provide a securely weldedconnection while minimally altering the footprint of the capacitor case.The overall volume of the device housing can thus be reduced.

In FIG. 85A, terminal wire 5030 with an expanded end 5040 at its end isattached directly to a capacitor case 5020 by, for example, arcpercussive welding or laser welding.

In FIG. 85B, expanded end 5040 is attached with braze 5016 to a piece ofintermediate material 5014 welded to the case 5020. Both methods ofattachment result in a low height profile that minimizes the amount ofinterconnect space required for connection of the capacitor to anexternal terminal.

In the capacitors described above, the case is electrically connected tothe cathode layers to form a negative case. In another embodiment, aterminal wire with an expanded end is attached to an anodic case whichis formed by the case inner surface being electrically connected to theanode layers of the capacitor, an example of which will be discussedbelow. Also, although the subject matter has been described above withreference to electrolytic capacitors, the subject matter may also beused in conjunction with other devices such as batteries or other typesof capacitors such as wet tantalum capacitors. The term capacitor, asused herein, should be interpreted to include those devices as well.

FIG. 86 illustrates a flat capacitor 6100 in accordance with oneembodiment of the present subject matter. Capacitor 6100 is similar tocapacitor 100 of FIG. 1, and as such, some details will be omitted forsake of clarity. Capacitor 6100 includes a case 6110, which containstherein a capacitor assembly 6108, which includes a capacitor stack6150. In one embodiment, case 6110 is an active case. “Active case”means herein that case 6110 is, in various embodiments, anodic orcathodic. In one embodiment, the case 6110 is manufactured from aconductive material, such as aluminum.

The capacitor stack 6150 includes anode stacks 6200 and cathode stacks6300, with separator layers interposed therebetween, as is furtherdiscussed below. The capacitor stack 6150 further includes a connector6130 which connects, in one embodiment, the cathode stacks 6300 withactive case 6110. In another embodiment, connector connects anodes 6200to the active case 6110.

The case 6110 further includes two components, a cover 6118 and a bottom6120, which are coupled together as part of the assembly process. In oneoption, the cover 6118 and the bottom 6120 are welded together.

By providing an active case, wherein the case acts as an anodic elementor a cathodic element, the capacitor 6100 can be made smaller whiledelivering the same amount of energy.

In one embodiment, the present subject matter provides a capacitorhaving an active cathodic case which services adjacent anodes. As usedherein, “service” means that the case is cathodic in the sense that itnot only is connected to the cathode stacks but literally services theanodes which are adjacent to the case. This means the case itselfreplaces one or two of the end cathodes which are usually present on thetwo outermost elements of the capacitor stack.

In this embodiment, case 6110 is comprised of at least 98% aluminum.Case 6110 has an inner surface 6112 which includes an upper innersurface 6114 and a lower inner surface 6116. At least a portion of theinner surface 6112 is etched, and in one option, the entire innersurface 6112 is etched. In one example, the inner surface 6112 of thecase 6110 is etched in the same way that a cathode conductive layer 6320(FIG. 90) is etched.

FIG. 87 illustrates one example of capacitor stack 6150 in greaterdetail. The capacitor stack 6150 includes a plurality of capacitorelements 6160, each capacitor element 6160 includes at least one anodestack 6200, at least one separator 6170, and one or more cathode stacks6300. In this embodiment, one of the cathode stacks is a cathode baselayer 6305.

Capacitor stack 6150 also includes an end anode stack 6202 and an endseparator 6172 which confront an inner surface 6112 of case 6110 (FIG.86) when stack 6150 is mounted within case 6110.

Each cathode stack 6300 is interconnected with the other cathode stacksin the capacitor stack 6150 and with base cathode layer 6305. Theinterconnected cathode stacks are electrically coupled with the case6110 through connection member 6120 of base cathode layer 6305. In thisembodiment, case 6110 is an active part of the cathode, as will bediscussed further below. In one embodiment, the cathode stack is asdescribed above in FIGS. 43-47. Other embodiments include aluminum tabsattached to each cathode layer. The tabs are connected together andconnected to case 6110.

Separator 6170 and 6172 include, but are not limited to, two sheets ofpaper separator. The separators are, in one embodiment, made from a rollor sheet of separator material. Suitable materials for the separatormaterial include, but are not limited to, pure cellulose or Kraft paper.Other chemically inert materials are suitable as well, such as porouspolymeric materials. The separator layers are cut slightly larger thanthe anode layers (or cathode layers) to accommodate misalignment duringthe stacking of layers and to prevent subsequent shorting betweenelectrodes of opposite polarity.

The interconnected cathode stack is electrically coupled with the case6110 (FIG. 86) which has an etched inner surface 6112 (FIG. 86).Capacitor stack 6150 includes an end anode stack 6202. Having an endanode stack 6202 which is serviced by the case 6110 eliminates the needfor outer cathode stacks. Since at least one cathode stack 6300 can beremoved, this results in a space savings of at least 0.0012 inches (anexample cathode thickness). Further, at least one less separator 6170 isneeded, resulting in savings of 0.0005 inches per side. In oneembodiment, a second cathode stack is removed from the other end of thecapacitor stack, resulting in an additional space savings of 0.0012inches for the foil and 0.0005 for the separator. Thus, an exemplaryspace saving is 0.0017 inches per side and/or 0.0034 inches for the bothsides. These space saving are variable in various embodiments dependingon the thickness of foil used for the cathodes. Furthermore, the presentcapacitor provides for a simplified capacitor having fewer components.

FIG. 89 illustrates an exploded view of the anode stack 6200 accordingto one embodiment. The anode stack 6200 includes an anode separator6210, at least one conductive layer 6220, and an edge connection memberor edge clip 6240 coupled with at least one of the conductive layers6220. In one option, the at least one conductive layer 6220 includes afirst conductive layer 6222, a second conductive layer 6224, and a thirdconductive layer 6226. The first conductive layer 6222 includes aclearance portion 6242 surrounding the edge clip 6240. Each of theconductive layers 6220 includes a major surface 6230 and a side surface6232.

FIG. 90 illustrates an exploded view of cathode base layer 6305according to one embodiment. Cathode base layer 6305 includes legs 6324,the number of which and location of which are varied depending on thecathode stack 6300. Legs 6324 are for interconnecting base layer 6305 tothe other cathodes 6300 of the capacitor stack. Cathode base layer 6305includes a cathode separator 6310 and a cathode conductive layer 6320.In one embodiment, the cathode conductive layer 6320 has an outerperimeter 6322 inset from the cathode separator edges 6312 so that theedge clip 6240 (FIG. 89) will not contact the cathode conductive layer6320. Since the outer perimeter 6322 is inset, this can help to preventa discontinuity on an edge 6228 of the anode stack 6200 (FIG. 89) frommaking contact with the conductive layer 6320 of the cathode stack 6300.This design also allows for more variations in tolerances which canoccur during the manufacturing of the anode stack 6200 and the cathodestack 6300. Attached or integral with cathode 6305 is connection member6120 for attaching cathode 6300 to case 6110.

FIG. 91 illustrates a cross-sectional view of the capacitor stack 6150within the case 6110. Although the discussion relates to an upperportion of the case, the view of the capacitor stack is substantiallythe same for a lower portion of the case, and therefore is not repeated.The capacitor stack 6150 includes one or more anode stacks 6200, whereeach anode stack 6200 includes, for example, a first conductive layer6222, a second conductive layer 6224, and a third conductive layer 6226.The anode stack 6200 further includes an anode separator 6210. Thelayers 6222, 6224, 6226 of the anode stack 6200 are coupled together. Inone embodiment, the layers are staked together as described above inFIGS. 9-11.

The major surface 6230 of the first conductive layer 6222 of the firstanode stack 6204 faces the etched upper inner 6114 surface of the case6110, separated form case 6110 by separator 6170. An electrolyte 6180 isdisposed between the major surface 6230 and the upper inner surface6114. The electrolyte 6180 facilitates storage of charge between theanode stack 6200 and the case 6110. The etched upper inner surface 6114of the case 6110 services the anode stack 6200 in the same way that acathode stack 6300 services the anode stack 6200. In one embodiment, thecapacitor stack 6150 includes a first anode stack 6204 having a majorsurface 6230 facing and adjacent the upper inner surface 6114, and asecond anode stack 6206 (FIG. 87) having a major surface 6230confronting the lower etched inner surface 6116 (FIG. 86), where thecase 6110 services both the first anode stack 6204 and the second anodestack 6206.

In one embodiment, an inner surface 6250 of the edge clip 6240 extendsalong the edges 6228 of the second and third conductive layers 6224,6226 of the anode stack 6200. The inner surface 6250 of the edge clip6240 also extends past the separator edge 6212 and the cathode separatoredge 6312. The edge clip 6240 also extends along the edge 6212 of theanode separator of an adjacent capacitor element 6160 until makingcontact and being connected with an adjacent edge clip 6240. A pluralityof edge clips stack on top of one another such that a bottom surface6244 of an edge clip 6240 contacts a top surface 6246 of an edge clip6240 of an adjacent capacitor element 6160.

The edge clip 6240 allows for greater design flexibility in the choiceof materials for the anode conductive layers 6220 as the conductivelayers remain essentially flat while the connection between anode stacks6200 is made. In addition, the edge clip 6240 assists in filling thecross section of the case with anodic surface area, and thus increasesthe overall percentage of space within the case occupied by anodicsurface area. This helps to increase capacitance of the capacitor,and/or allows for the capacitor to be made smaller.

Some embodiments omit edge clips 6240, and interconnect the anode stacks6200 with tabs which are attached to or integral with each anode stack.

In one embodiment, edge clips 6240 are interconnected and coupled tofeedthrough 6280 (FIG. 86), which is insulated from case 6110. Inaddition, the feed through opening 6282 (FIG. 86) is sealed.

One example of a method for forming a capacitor having an activecathodic case is as follows. The method includes forming and aligning acapacitor stack including at least one anode stack and at least onecathode stack, etching at least a portion of an inner surface of acapacitor case, the inner surface including an upper inner surface and alower inner surface. The method further includes disposing the capacitorstack in the capacitor case, and an at least one anode stack is adjacentthe inner surface of the capacitor case. The method also includesdisposing an electrolyte between the at least one anode and the innersurface of the case.

Several options for the method are as follows. For instance, in oneembodiment, the method includes etching layers of the anode stack. Inanother embodiment, the method further includes confronting a majorsurface of a first anode stack with the upper inner surface of the case.In yet another embodiment, the method includes confronting a majorsurface of a second anode stack with the lower inner surface of thecase. Optionally, the method includes etching an entire inner surface ofthe case.

In another example of manufacturing the above described cathodic casecapacitor, a capacitor case is formed, including a case cover and a casebottom, and the inner surface of the capacitor case is etched. A stackof cathode and anode layers are stacked and aligned to form a capacitorstack. The cathode ledges are welded and folded over the stack. Thecapacitor stack is taped, and the anode edge clips are welded. An anodefeed through is welded to the edge couplers. The capacitor stack isinserted into the capacitor case, and the case cover and cathode legextension is welded to the case bottom.

Advantageously, the etched inner surface of the case increases cathodicsurface area on an existing surface. The etched inner surface allows forreduction of cathode stacks within the case by allowing at least oneouter cathode stack to be removed, which in turn allows for the size ofthe capacitor to be reduced. Alternatively, the anodic surface areawithin the case can be increased and the total capacitance of thecapacitor can be increased.

In one embodiment, the capacitor has an active anodic case. Referringagain to FIG. 86, in one embodiment, case 6110 comprises 99.99%aluminum. In another embodiment, the case comprises at least 98%aluminum. In one embodiment, at least a portion of the inner surface6112 is etched, and in one embodiment, the entire inner surface 6112 isetched.

FIG. 91 illustrates a capacitor stack 6650 according to one embodimentof the present subject matter. Capacitor stack 6650 is mountable in case6110 similarly to stack 6150.

In this embodiment, capacitor stack 6650 includes a plurality ofcapacitor elements 6160, each capacitor element 6160, except for the endcapacitor elements, includes at least one anode stack 6200, at least oneseparator 6170, and at least one cathode stack 6300. The capacitor stack6650 includes end separators 6172. Each cathode stack 6300 isinterconnected with the other cathode stacks in the capacitor stack6650. Each anode stack 6200 is interconnected with the other anodestacks in the capacitor stack 6650.

The at least one separator 6170 and the end separator 6172 include, butare not limited to, a paper separator. The separators are, in oneoption, made from a roll or sheet of separator material. Suitablematerials for the separator material include, but are not limited to,pure cellulose or Kraft paper. Other chemically inert materials aresuitable as well, such as porous polymeric materials. The separatorslayers can be cut slightly larger than the anode layers (or cathodelayers) to accommodate misalignment during the stacking of layers and toprevent subsequent shorting between electrodes of opposite polarity.

Referring again to FIG. 88, in one embodiment, anodes 6200 includes oneor more conductive layers 6220. Each of the conductive layers 6220includes an outer edge surface 6218, which define an outer edge of thecapacitor stack 6650 (FIG. 91). In one option, the outer edge surface6218 of at least one of the conductive layers 6220 is exposed and iselectrically coupled with the inner surface 6112 of the case 6110 (FIG.86), as will be discussed further below.

FIG. 92 illustrates an exploded view of a cathode stack 6306 in greaterdetail. The cathode stack includes legs 6324, the number of which andlocation of which is varied depending on the cathode stack 6300. Thecathode stack 6300 includes a cathode separator 6310 and a cathodeconductive layer 6320. The cathode conductive layer 6320 has an outerperimeter 6322 inset from the cathode separator edges 6312 so that theedge clip 6240 (FIG. 88) will not contact the cathode conductive layer6320. Since the outer perimeter 6322 is inset, this can help to preventa discontinuity on an edge 6228 of the anode stack 6200 (FIG. 88) frommaking contact with the conductive layer 6320 of the cathode stack 6300.This design also allows for more variations in tolerances which canoccur during the manufacturing of the anode stack 6200 and the cathodestack 6300.

FIG. 93 illustrates a cross-sectional view taken along 8-8 of FIG. 94,which shows a capacitor 6100. The capacitor stack 6650 is disposedwithin the capacitor case 6110. The inner surface 6112 of the capacitorcase 6110 includes a dielectric 6180 formed thereon. In this embodiment,the perimeter 6174 of each separator 6170 and 6172 contacts the innersurface 6112 of the case 6110. In addition, the outer perimeter 6322(FIG. 92) of the cathode stack 6300 is inset from the perimeter 6174 ofthe separator 6170. In one embodiment, the major surface 6230 of thefirst anode stack 6204 faces the etched upper inner 6112 surface of thecase 6110.

Outer edge surface 6218 of at least one anode stack 6200 contacts theinner surface 6112 of the case 6110. In one option, the outer edgesurface 6218 is exposed and electrically coupled with the inner surface6112 of the case 6110, for example, by intimate contact. In anotheroption, the anode stack 6200 is coupled with the inner surface 6112 ofthe case 6110 in other manners. For example, the anode stack 6200 iscoupled at 6182 with the inner surface 6112 by welding the anode stack6200 with the inner surface 6112. In another example, the anode stack6200 is coupled at 6182 with the inner surface 6112 by bonding the anodestack 6200 with the inner surface 6112, for example, using epoxy orother bonding materials.

FIG. 95 shows an anode 1001 having a tab connector 6090 according toanother embodiment. In this embodiment, one anode in capacitor stack6650 includes a tab connector 6090. The other anodes in the capacitorstack are interconnected and tab connector 6090 is coupled to case 6110.In some embodiments, multiple anodes have tab connectors 6090. In oneembodiment, tab connector is welded to anode 1001.

FIG. 96 illustrates a capacitor stack 6650 including a cathode extensionleg 6328. In this embodiment, the cathode extension leg 6328 extendsfrom the bottom cathode stack 6304 below the bottom edge clip 6240. Thecathode extension leg 6328 is insulated from the edge clip 6240 by aninsulator 6190 included on the inner surface of the cathode extensionleg 6328. The cathode extension leg 6328 is folded over the edge clips6240 and coupled to a feedthrough 6380 (FIG. 86). After connection tothe feedthrough 6380, the exposed portion of the cathode extension legoptionally is insulated to prevent contact with the anodic case 6110.

The cathode stacks 6300 include cathode interconnect legs 6324. In analternative option, a feedthrough 6380 (FIG. 86) is coupled to one ofthe legs 6324 and the remaining exposed portion is covered by insulator6192 (FIG. 97).

FIGS. 97 and 98 illustrate the capacitor stack 6650 where the anodestack 6200 (FIG. 91) is coupled with the case 6110 (FIG. 86). Thecapacitor stack 6650 includes an anode extension leg 6290 coupled to theouter contact surface of the edge clips 6240. The cathode extension leg6328 is folded over the anode extension leg 6290 and is insulated fromthe anode extension leg 6290 by insulator 6190. The outer surface of thecathode extension leg 6328 is suitable for receiving a feedthroughconnection. After connection to a feedthrough, the exposed portion ofthe cathode extension leg 6328 is insulated to prevent contact with theanodic case 6110. The capacitor stack 6650 includes insulator 6192 overcathode interconnect legs 6324.

FIG. 99 illustrates a cross-sectional view of a portion of the capacitorstack 6650. In this embodiment, the connection between the edge clips6240 and the case 6110 is with the anode extension leg 6290. The anodeextension leg 6290 is coupled to and extends from the interconnectededge clips 6240. Each edge clip 6240 includes an outer contact surface6248, which provides a larger contact surface that is more easilyattached to an anode extension leg 6290 than existing methods ofattachment. The anode extension leg 6290, in one option, is sufficientlyductile to be deformed to extend along the side of the capacitor stack6150 and between the interface between the case cover 6110 and the casebottom 6120. As mentioned above, the cathode extension leg 6328 foldsover the anode extension leg 6290 and is insulated from the anode stacks(FIG. 91) and anode extension leg 6290 by insulator 6190.

FIG. 100 shows a cross-section of section 15-15 of FIG. 94. The outersurface of the cathode extension leg 6328 is coupled to a cathodefeedthrough 6380. An insulator 6384 is included over the remainingexposed portion of the outer surface of the cathode extension leg 6328.The cathode feedthrough 6380 is welded to the outer surface of thecathode extension leg 6328, and the cathode feedthrough 6380 isinsulated from the case 6110 (FIG. 86). The feedthrough opening 6382(FIG. 86) is sealed.

One aspect of the present embodiment provides a method of manufacturing.In one embodiment, a method includes stacking at least one anode stackincluding one or more conductive anode layers and an anode separator,stacking at least one cathode stack including one or more conductivecathode layers and a cathode separator, aligning and stacking the atleast one anode stack and the at least one cathode stack to form acapacitor stack, disposing the capacitor stack within a capacitor case,and electrically coupling the anode stack with the capacitor case.

Several options for the method are as follows. For example, in oneembodiment, the method further includes etching an inner surface of thecapacitor case, and/or etching the one or more conductive anode layers.In another embodiment, the method further includes welding the anodestack with the capacitor case, or bonding the anode stack with thecapacitor case. In a further embodiment, the method further includescoupling a cathode feedthrough with the cathode stack, and disposing thecathode feedthrough through an opening of the capacitor case. In anotherembodiment, the method further includes stacking the conductive cathodelayer in an offset position from the anode conductive layer, and/orexposing outer edges of the one or more conductive anode layers. In yetanother embodiment, the method further includes coupling the exposedouter edges with the capacitor case, and/or welding the exposed outeredges with the capacitor case.

In another example of manufacturing the above described capacitor, acapacitor case is formed, including a case cover and a case bottom, andoptionally the inner surface of the capacitor case is etched. A stack ofcathode and anode layers are stacked and aligned to form a capacitorstack. The cathode legs are welded and folded over the stack. Thecapacitor stack is taped, and the anode edge clips are welded. An anodeleg is welded to the edge clips, and the cathode feedthrough is weldedto the cathode extension leg. The capacitor stack is inserted into thecapacitor case, and the case cover and the anode extension leg arewelded to the case bottom. An anode ribbon is welded to the case, andthe opening for the feedthrough is sealed.

Advantageously, having the case contribute to the effective anodicsurface area increases the capacitance of the capacitor withoutincreasing the outer packaging dimensions. Alternatively, it allows forachievement of a given total capacitance with a smaller package. Afurther benefit is that since the edge of the cathode stack is offsetfrom the anode stack, damage or puncturing of the separator layer isminimized.

Referring again to FIG. 1, in one embodiment, each anode is connected tothe other anodes of the capacitor and coupled to feedthrough assembly103 for electrically connecting the anode to circuitry outside the case.Various example methods of interconnecting the anode foils and/orcathode foils-have been discussed. For instance, in some embodiments,interconnections are provided as discussed above for FIGS. 12-15, 43-47,56-57, and/or 83-84.

FIGS. 101-105 discuss another embodiment for providing interconnections.FIG. 101A shows an anode 7202 according to one embodiment of the presentsubject matter. Anode 7202 is shown before it is assembled intocapacitor stack 7102 as shown in FIG. 1. Anode 7202 includes a main bodyportion 7204 having one or more connection members 7206. In oneembodiment, connection member 7206 includes one or more separate membersattached to the anode by welding, staking, or other connection method.

In other embodiments, connection member 7206 is an integral portion ofanode 7202, and is punched, laser-cut, or otherwise shaped from theanode foil. In such an embodiment, portions of connection member 7206are not etched along with the rest of anode 7202. For instance, achemical mask is put on portions of connection member 7206 to keep thosemasked portions from becoming etched during the etching process. As willbe discussed below, this provides that those unetched, non-poroussections make welding the edges of the anodes to each other easier.

Connection member 7206 includes a proximal section 7208 and distalsection 7210. In the embodiment of FIG. 2A, connection member 7206 is anL-shaped member. However, it can also be hook shaped, U-shaped, and/orhave other shape. In one embodiment, a portion of a distal section 7210along its outer edge is unetched, as discussed above.

In one embodiment, proximal section 7208 is connected to main body 7204and is defined in part by a pair of cut-out portions 7212 and 7214located on opposing sides of proximal section 7208. Distal section 7210is connected to a portion of proximal section 7208. In one embodiment,it is integral with proximal section 7208. In some embodiments, distalsection 7210 is attached as a separate member. In one embodiment, distalsection 7210 is defined in part by a cut-out portion 7216 which islocated between main body 7204 and distal section 7210, and a cut-outportion 7218 which separates distal section 7210 from main body 7204.

In this embodiment, connection member 7206 is located within the generalperimeter or outline of anode 7202. In other embodiments, connectionmember extends further from the main body of anode 7202 or connectionmember 7206 is more internal within the main body of anode 7202.

In some embodiments, each anode foil in capacitor stack 7102 includes aconnection member such as connection member 7206. In other embodiments,one or more anode foils in a multi-anode stack have a connection member7206 while the other anode foils in the multi-anode stack are connectedto the anode having the connection member. For instance, in oneembodiment, a three-foil anode stack includes one foil having aconnection member 7206 and two foils without connection members. The twofoils without connection members are welded, staked, or otherwiseattached to the foil having the connection member.

FIG. 101B shows a cathode 7302 according to one embodiment of thepresent subject matter. Cathode 7302 is shown before it is assembledinto capacitor stack 7102 as shown in FIG. 1. Cathode 7302 includes amain body portion 7304 having one or more connection members 7306. Inone embodiment, connection member 7306 is an integral portion of cathode7302, and is punched, laser-cut, or otherwise shaped from the anodefoil. In one embodiment, connection member 7306 includes one or moreseparate members attached to the anode by welding, staking, or otherconnection method.

In one embodiment, connection member 7306 includes a proximal section7308 and a distal section 7310. In the embodiment of FIG. 101B,connection member 7306 is an L-shaped member. However, additionalembodiments include hook shapes, U-shapes, and other shapes.

In one embodiment, proximal section 7308 is connected to main body 7304and is defined in part by a pair of cut-out portions 7312 and 7314located on opposing sides of proximal section 7308. Distal section 7310is connected to a portion of proximal section 7308. In one embodiment,it is integral with proximal section 7308. In some embodiments, distalsection 7310 is attached as a separate member. In one embodiment, distalsection 7310 is defined in part by a cut-out portion 7316 which islocated between main body 7304 and distal section 7310, and a cut-outportion 7318 which separates distal section 7310 from main body 7304.

In this embodiment, connection member 7306 is located within the generalperimeter or outline of cathode 7302. In other embodiments, connectionmember 7306 extends further from the main body of cathode 7302 orconnection member 7306 is more internal within the main body of cathode7302.

FIGS. 102A and 102B show an anode 7202′ and a cathode 7302′ according toone embodiment of the present subject matter. Anode 7202′ and cathode7302′ are shown before they are assembled into capacitor stack 7102 asshown in FIG. 1. Anode 7202′ and cathode 7302′ are generally similar toanode 7202 and cathode 7302, respectively, except a connection member7206′ does not include a cut-out such as cut-out 7212 of anode 7202 andconnection member 7306′ does not include a cut-out such as cut-out 7318of cathode 7302. Other embodiments utilize other shapes and locationsfor connection members such as connection members 7206, 7206′, 7306, and7306′.

For instance, in various embodiments, connection members 7206 and 7306may be in different positions along the edges or even within the mainbody portions of the capacitor foils 7202 and 7302. For instance, insome embodiments, connection members 7206 and 7306 are located alongedges 7220 and 7320 of the respective foils 7202 and 7302. In someembodiments, the portions are located along curved edges 7222 and 7322of the respective foils 7202 and 7302. In other embodiments, theportions may be cut-out within main bodies 7204 and 7304.

In one embodiment, proximal section 7308 of cathode 7302 and proximalsection 7208 of anode 7202 are located in different positions (relativeto each other) on their respective foils, while distal sections 7210 and7310 are generally commonly positioned. For instance, in one embodimentconnection members 7206 and 7306 of the anode 7202 and the cathode 7302,respectively, are mirror images of each other.

In some embodiments, connection members 7206 and 7306 have generallyreverse images of each other.

FIG. 103 shows a stack 7402 of one or more alternating anodes 7202 andcathodes 7302. As shown in FIG. 103, connection members 7206 and 7306are overlaying and underlying each other. As used herein, overlay andunderlay refer to the position or location of portions of the foilswhich are commonly positioned from a top view. In the embodiment of FIG.103, it is seen that connection members 7206 and 7306 have some commonlypositioned portions relative to each other and some portions which areexclusively positioned relative to each other.

For instance, proximal sections 7208 of anodes 7202 are exclusivelypositioned or located. This means that at least a portion of proximalsections 7208 do not overlay or underlay a portion of cathodes 7203.Likewise, proximal sections 7308 of cathodes 7302 are exclusive portionsand include at least a portion not overlaying or underlaying a portionof anode 7202. Conversely, distal sections 7210 and 7310 are commonlypositioned and each includes at least a portion overlaying or underlyingeach another. Cut-out portions 7214 and 7314 are also commonlypositioned. Cut-out 7218 is commonly positioned with cut-out 7312 whilecut-out 7212 is commonly positioned with cut-out 7318.

When stacked as shown in FIG. 103, the edges of distal sections 7210 and7310 form a surface 7410. In this embodiment, surface 7410 can generallybe described as having a first portion 7410 a which fronts the proximalsections 7208 of anodes 7202, a second portion 7410 b which frontscommon cut-portions 7214 and 7314, and third portion 7410 c which frontsthe proximal sections 7308 of cathodes 7302.

In this embodiment, distal sections 7210 and 7310 of anode connectionmember 7206 and cathode connection member 7306 are fully overlaying oneanother. Fully overlaying means that there are generally no gaps alongsurface 7410 of stack 7402 when the anodes and cathodes are stacked asin FIG. 103. The fully overlayed structure of stack 7402 provides acomplete surface 7410 which provides for ease of edge-welding orotherwise connecting connection members 7206 and 7306 together, as willbe described below. Other embodiments leave one or more gaps in surface7410 when the anodes and cathodes are stacked. For instance, in someembodiments, one or more of distal sections 7210 or 7310 may not reachall the way across front surface 7410.

After being stacked as discussed above, at least portions of connectionmembers 7206 and 7306 are connected to each other. For instance, in oneembodiment portions of distal sections 7210 and 7310 are connected toeach other. In one embodiment, distal sections 7210 and 7310 areedge-welded all along surface 7410. In one embodiment, distal sections7210 and 7310 are only connected along portion 7410 a and 7410 c ofsurface 7410. In one embodiment, distal sections 7210 and 7310 aresoldered along surface 7410. In some embodiments, portions of distalsections 7310 and 7210 are staked, swaged, laser-welded, or connected byan electrically conductive adhesive. In other embodiments, portions ofproximal sections 7208 are connected to each other and/or portions ofproximal sections 7308 are connected to each other.

After being connected, portions of connection members 7206 and 7306 areremoved or separated so that proximal sections 7208 and 7308 areelectrically isolated from each other. As used herein, electricallyisolated means that sections 7208 and 7308 are electrically insulatedfrom each other at least up to a surge voltage of capacitor 7100.

FIG. 104A shows stack 7402 after portions of distal sections 7210 and7310 have been removed from the stack, forming a separation 7502 betweenanode connection members 7206, which together comprise anode connectionsection 7508, and cathode connection members 7306, which togethercomprise cathode connection section 7510. Separation 7502 in the presentembodiment electrically isolates section 7508 from section 7510.Proximal sections 7308 are still coupled to each other as are proximalsections 7208. In some embodiments, separation 7502 is a thin slice. Insome embodiments, separation 7502 is as wide as cut-outs 7214 and 7314,as shown in FIG. 104. In some embodiments, an electrically insulativematerial is inserted in separation 7502. In various embodiments,separation 7502 is formed by laser cutting, punching, and/or tool ormachine cutting.

FIG. 104B shows a stack 7402B of one or more alternating anodes 7202 andcathodes 7302B, in accordance with one embodiment. Anodes 7202 are asdiscussed above. In this example, cathodes 7302B can include thefeatures discussed above for other cathodes and the above discussion isincorporated herein. Cathodes 7302B have a shorter distal section 7310Bthan the example discussed above in FIG. 104A, for example. Distalsection 7310B can be L-shaped as discussed above or the connectionmember can be straight out from the cathode body forming an I-shape. Asshown in FIG. 104B, connection members 7206 and 7306B include at least aportion that is overlaying and underlying each other. As noted above,overlay and underlay refer to the position or location of portions ofthe foils which are commonly positioned from a top view. In theembodiment of FIG. 104B, it is seen that connection members 7206 and7306B have some commonly positioned portions relative to each other andsome portions which are exclusively positioned relative to each other.

For instance, proximal sections 7208 of anodes 7202 are exclusivelypositioned or located. This means that at least a portion of proximalsections 7208 do not overlay or underlay a portion of cathodes 7302B.Likewise, in one embodiment, proximal sections 7308B of cathodes 7302Bare exclusive portions and include at least a portion not overlaying orunderlying a portion of anode 7202. Moreover, in this example, distalportion 7310B of cathodes 7302B does not extend across the entire distalportion 7210 of the anodes 7202. Distal sections 7210 and 7310B doinclude a commonly positioned portion along portion 7410 c where eachinclude at least a portion overlaying or underlying each another.Cut-out portions 7214 and 7314B are also commonly positioned. Cut-out7218 is commonly positioned with cut-out 7312B while cut-out 7212 iscommonly positioned with cut-out 7318B.

When stacked as shown in FIG. 104B, the edges of distal sections 7210and 73101B form a surface 7410S. In this embodiment, surface 7410S cangenerally be described as having a first portion 7410 a which fronts theproximal sections 7208 of anodes 7202, a second portion 7410 b whichfronts common cut-portions 7214 and 7314B, and third portion 7410 cwhich fronts the proximal sections 7308B of cathodes 7302B.

In this embodiment, distal sections 7210 and 7310B of anode connectionmember 7206 and cathode connection member 7306B are overlaid relative toeach other such as to be not continuous across surface 7410S, with anodeconnection members 7206 reaching across surface 7410S but cathodeconnection members 7306B not reaching across the surface. In otherembodiments, the reverse can be true and the cathode connection membercan reach across while the anode connection member is shorter and doesnot reach across.

After being stacked as discussed above, at least portions of connectionmembers 7206 and 7306B are connected to each other. For instance, in oneembodiment portions of distal sections 7210 and 7310B are connected toeach other. In one embodiment, distal sections 7210 and 7310B areedge-welded all along surface 7410S. In one embodiment, distal sections7210 and 7310B are only connected along portion 7410 a and 7410 c ofsurface 7410S. In one embodiment, distal sections 7210 and 7310B aresoldered along surface 7410S. In some embodiments, portions of distalsections 7310B and 7210 are staked, swaged, laser-welded, or connectedby an electrically conductive adhesive. In other embodiments, portionsof proximal sections 7208 are connected to each other and/or portions ofproximal sections 7308B are connected to each other.

After being connected, portions of connection members 7206 and 7306B areremoved or separated so that proximal sections 7208 and 7308B areelectrically isolated from each other. As used herein, electricallyisolated means that sections 7208 and 7308B are electrically insulatedfrom each other at least up to a surge voltage of capacitor 100 (FIG.1). For example, dashed lines 7451 and 7453 define an example of an areathat can be removed to electrically isolate the anodes and the cathodes.In various embodiments, different areas can be removed. For example, inone embodiment, a portion of the distal ends 7210 of the anodes areremoved and the cathode distal sections are not removed at all. Inanother embodiment, a portion of the commonly positioned section 7410 ccan be removed. Some examples include removing a portion of the distalsection 7210 of the anode connection member 7206 and a portion of thedistal section 7310B of the cathode connection member 7306B. Someexamples include removing a portion of the distal section 7210 of theanode connection member 7206 such that there remains no material orsection of the cathode connection member 7306B adjacent the anodeconnection member 7206.

FIG. 104C shows stack 7402B after portions of distal sections 7210 havebeen removed from the stack, forming a separation 7502 between anodeconnection members 7206, which together comprise anode connectionsection 7508B, and cathode connection members 7306B, which togethercomprise cathode connection section 7510B. Separation 7502 in thepresent embodiment electrically isolates section 7508B from section7510B. Proximal sections 7308B are still electrically coupled to eachother as are proximal sections 7208. In one embodiment, the separationis performed such that cathode connection members 7306B include someanode material between each layer, while anode connection members 7206do not include any cathode material between the layers.

In some embodiments, separation 7502 is a thin slice. In someembodiments, separation 7502 is as wide as cut-outs 7214 and 7314B, asshown in FIG. 104B. As noted, some examples include removing a portionof the distal section of the anode connection member 7206 such thatthere remains no portion or material of the cathode connection memberadjacent the anode connection members 7206. This is advantageous sincein some examples the cathode layers can include a titanium coating, forexample. A titanium coating can interfere with the performance of theanodes or can cause an electrical leakage into the weld or connectionbetween the anodes. The present example keeps all cathode material outof the anode side 7508B. In some embodiments, an electrically insulativematerial is inserted in separation 7502. In various embodiments,separation 7502 is formed by laser cutting, punching, and/or tool ormachine cutting.

FIG. 105 shows a flowchart depicting a method 7600 for interconnectingtwo or more foils of a capacitor according to one embodiment of thepresent subject matter. Method 7600 includes a block 7602, positioningthe connection members of two or more foils, a block 7604, connectingthe connection members, and block 7606, electrically isolating portionsof the connection members from each other.

In one embodiment, block 7602, positioning the connection members of twoor more foils, includes stacking an anode foil having a connectionmember having a proximal section and a distal section upon a cathodefoil having a connection member having a proximal section and a distalsection. The foils and connection members are positioned so that theproximal section of the anode foil connection member does not overlaythe proximal section of the cathode foil connection member and thedistal section of the anode foil connection member at least partiallyoverlays the distal section of the cathode foil connection member.

In one embodiment, block 7604, connecting the connection members,includes connecting the connection member of the anode foil to theconnection member of the cathode foil. In one embodiment, this includesconnecting the distal section of the anode connection member and thedistal section of the cathode connection member at a portion of theanode connection member that overlays (or underlays) the portion of thecathode connection member. In one embodiment, connecting comprises asingle, continuous connection process. For instance, a laser weld orstaking process is performed which attaches all the anode and cathodefoil connection members together during a single, uninterrupted process.In one embodiment, the connection is performed by edge-welding at leasta portion of the distal sections of the anode foil and the cathode foiltogether. One embodiment includes a laser edge-welding process.

Alternatively, in some embodiments, a portion of the stack is weldedduring a different process or by a different method than the firstprocess. Some embodiments include soldering, staking, swaging, and/orapplying an electrically conductive adhesive. In one embodiment,connection members 7206 and 7306 are laser edge-welded to each other bythe edge-welding process discussed above.

In one embodiment, block 7606, electrically isolating portions of theconnection members from each other, includes removing portions of theanode connection member and the cathode connection member. In oneembodiment, the removed portion includes where the cathode connectionmember overlays (or underlays) a portion of the anode connection member.In one embodiment, this includes removing a portion of the distalsections of the anode connection member and the cathode connectionmember. In one embodiment, electrically isolating comprises punching-outa portion of the distal section of the anode foil connection member andthe distal section of the cathode foil connection member. In oneembodiment, electrically isolating includes laser cutting a portion ofthe distal section of the anode connection member and the distal sectionof the cathode connection member.

After being processed as discussed above in block 7606, proximalsections 7208 of the connection members of anodes 7202 are still coupledtogether and proximal sections 7308 of the connection members ofcathodes 7302 are still coupled to each other, while the anodes 7202 andcathodes 7302 are electrically isolated from each other. Feedthroughs orother terminal members are then used to couple the anodes and cathodesto outside circuitry. Among other advantages, the present example methodreduces the number of processing steps for constructing a capacitor.

One aspect of the present capacitor includes a system forinterconnecting anode layers in a flat capacitor stack using vias. Inone embodiment, vias are employed to interconnect anode layers. In oneembodiment, the vias are made by inserting conductive interconnectswhich interconnect anode layers without contacting an interveningcathode layer.

For example, FIG. 106A shows a top view of a cathode and anode layerseparated by separator (for example, kraft paper). The cathode layerincludes one or more holes which provide ample clearance for aconductive interconnect. The x-section of FIG. 106A, shown in FIG. 106B,shows that the conductive interconnect will interconnect anode layerswithout contacting an intervening cathode layer. Thus, the cross sectionof the cathode hole exceeds that of the conductive interconnect to avoidshorting the cathode to the anodes. The conductive interconnect iselectrically connected to the anodes by welding, such as ultrasonic,resistance or other types of welding.

One way to facilitate connections is to use a masking process forconnection surfaces on the foil to ensure that the masked surfaces arenot etched and/or formed. One way to avoid mechanical breakage of thefoils is to use a masking technique which provides gradually non-etchedportions of the foil to avoid mechanical stresses (e.g. high stresspoints) due to discontinuities of etching and which provides a suitableregion for interconnection of the via to the foil. This is demonstratedby FIG. 106C. The vertical lines show the cross-section of unmasked andmasked foil portions. The FIG. shows that foil etching graduallydiminishes over the transition from masked portion to unmasked portion.It is noted that the example shows a pure aluminum foil, but that otheretchings and foils may be masked without departing from the scope of thepresent system.

FIG. 106D shows a side view of a foil and positions of the masks for oneembodiment of the present system. The top view is provided in FIG. 106E.The positions, shapes and sizes of the masks may vary without departingfrom the present system, and the demonstrated masks are shown toillustrate the system and are not intended in an exhaustive or exclusivesense. In one embodiment, thickness t is 100 micrometers. However, it iscontemplated that other thicknesses may be used without departing fromthe present system. For example, other thicknesses, including, but notlimited to, 50-600 micrometers may be used.

The foil dimensions are shown as 500×250 millimeters, but other sizedfoils may be employed without departing from the scope of the presentsystem. In one application of the present system, a master roll of foilis masked to provide d-shaped cutouts with accurately placed masks wherethe conductive interconnects are to contact the foil. In oneapplication, the spacing between foils must be large enough to provide a“web” for processing the cutouts.

FIG. 106F shows one process for providing one embodiment of a capacitoraccording to some of the teachings herein. Raw foil is masked byprinting the mask on the foil. The masked foil is etched and then themask is removed. Oxides are formed on the foil and it is then cut intosubrolls. The subrolls are processed by cutting shapes for the finalcapacitor out of the subrolls. The foil shapes are used to make thecapacitors.

The cathode foils are processed to accurately place the cathode holes,which correspond to anode mask layers when overlapped. Paper separatorsare also cut to provide space for the conductive interconnects. In oneapplication, the perimeter of the paper is smaller than that of thecathode to provide a nonconductive guide for the conductiveinterconnect. In alternate embodiments, an insulator may be used toposition the conductive interconnect and to insulate against cathodecontact.

It is noted that the conductive interconnects may be connected to formedor unformed portions of the anode layer.

One way to manufacture a capacitor according to the present teachings isto use a robotic assembly method, whereby anodes which are alreadymasked, etched, and formed are stacked, followed by separator material,and then cathode material. In one assembly process, the cathodes areprecision punched to provide accurately placed cathode holes. The robotcan use the cathode features to accurately place the cathode relative tothe anodes. A separator layer and an anode layer are also placed overthe cathode using the robot. In embodiments where the conductiveinterconnect is a metal plug, the robot places the conductive plugaccurately prior to the placement of the separator and anode layers.This process may be repeated to provide a stack of anodes of multiplelayers interspersed with separator and cathode layers. The robot canalso be used to perform the welding steps.

Other types of conductive interconnects may be used without departingfrom the present system. For example, the conductive interconnects maybe made of a non-circular cross section. The conductive interconnectsmay be made of a suitable metal, such as aluminum. The conductiveinterconnects may also be made of other materials, including, but notlimited to, conductive epoxy, conductive polymer (such as polyimidefilled with aluminum), or fused aluminum powder. The metal used in theconductive interconnect should match the anode metal. Other anodemetals/interconnect metal pairs may be used including, but not limitedto, tantalum, hafnium, niobium, titanium, zirconium, or combinations ofthese metals.

It is understood that other connections may be performed using theteachings provided herein. For example, it is possible to create aseries of interconnections between cathode layers using the teachingsprovided. Thus, use of the present system is not limited to anode-anodeconnections.

In one embodiment, the anode layers consist of a plurality of anodefoils. In one application is it is possible that a single anode foil isinterconnected to a triple anode foil or any multiplicity of anode foilcombinations.

In one embodiment an anode layer may include a plurality of parts and/orlayers. For example, the anode layer may include two different anodeshapes in the same layer to provide a contoured edge. The shapes may beelectrically connected to provide an equipotential surface. The use ofmultiple anode parts for a single layer facilitates the construction ofa capacitor of virtually any form factor.

Furthermore, it is possible to weld multiple anode-cathode-anode stacksat different points for different conductive interconnects in oneoperation. Additionally, depending on the welding process used, severalanode/cathode layers can be welded in a single operation.

Some of the benefits of the present system include, but are not limitedto, the following: the electrical connection system provides mechanicalstability; and alignment to the stack as the layers are being assembled;taping is not required; the assembly is ready for insertion into thecapacitor case; surface area is optimized; interior alignment isfacilitated using interior features to align the stack layer to layer;edge-welding and/or intra-anode staking may be eliminated; and, in someembodiments, paper gluing may be eliminated.

In one embodiment, a multi-chamber capacitor case is provides. Mostimplantable medical devices employ two capacitors that are separatelycharged with an inductive boost converter and connected in series todeliver a shock pulse. Packaging two energy storage capacitors in animplantable medical device housing, however, means fitting two bulkycapacitor cases into the housing because each capacitor includes a stackof capacitive elements enclosed in its own case. Simply increasing thenumber of capacitive elements in the case does not solve the problem,because all of the electrolyte in the case is at the same electricalpotential. This prevents the capacitive elements in the case from beingconnected electrically in series. To provide a series connection,therefore, two separate capacitors with isolated electrolytes must beused. This can be accomplished with greater space efficiency byemploying a capacitor case having two (or more) separate compartmentsfor containing separate stacks of capacitive elements.

FIG. 107A is a schematic representation of one embodiment of anelectrolytic capacitor. A case 8010 has two compartments 8020 a and 8020b for containing two separate stacks 8030 a and 8030 b of capacitiveelements. The two stacks are stacked vertically in their respectivecompartments, and a common wall 8021 separates the two compartments.Each capacitive element in a stack includes an anode 8032, a separator8033, and a cathode 8034 that are arranged in a layered structure, withthe separator interposed between the anode and cathodes. An electrolytically formed oxide layer on the anode serves as the insulating dielectricfor the capacitor. The separator is impregnated with an electrolyte thatserves as the cathode for the capacitor, with the cathode platesupplying current to the electrolyte. If the case 8010 is made of ametallic conductive material, an insulating coating can be applied tothe inner surface of each compartment to electrically isolate theelectrolyte from the case. One means of doing this is to electrolytically apply an oxide coating to the inner walls of the compartments.

When a voltage is applied so that the anode plate is made positiverelative to the cathode plate, the element acts as a capacitor bydropping a voltage across the oxide layer of the anode plate that isproportional to the charge stored on the plates. Extending tabs fromeach cathode and anode plate of the stack in compartment 8020 a are usedto electrically connect like types of plates to separate conductors. Forinstance, the capacitor stack can include tabs which extend from thecathode and anode plates, respectively, as discussed above. Conductorscan be connected to the tabs respectively, and be routed via feedthroughholes (i.e., passages in the wall of the case) to connect to a cathodeterminal 8037 a or an anode terminal 8038 a. A voltage applied to theterminals then sees a capacitance equal to the sum of the capacitancesof the capacitive elements in the stack (i.e., the elements areconnected in parallel). In a like manner, conductors can be provided forthe stack in compartment 8020 b which are terminated at a cathodeterminal 8037 b and an anode terminal 8038 b. The two stacks can then beconnected together in series by connecting unlike terminals from eachstack together. For example, in FIG. 107A, terminal 8038 a can beconnected to terminal 8037 b. A voltage applied across terminals 8037 aand 8038 a then sees a capacitance equal to the desired seriesconnection of the two stacks.

The above description was with reference to a stacked flat type ofcapacitor. In the case of a cylindrical capacitor, each strip of foilhas an attached aluminum tab extending out of the rolled assembly towardthe top of the tubular case, which is sealed shut with a lid called aheader. Extending from the header are cathode and anode terminals whichare connected respectively to the two foils via the aluminum tabs. Twosuch cylindrical capacitors in separate compartments can then beconnected together in series in the same manner as described above.

FIG. 107B schematically shows another embodiment where the samereference numerals as in FIG. 107A are used to identify the componentparts. In this embodiment, however, the cathode plates of onecompartment and the anode plates of the other compartment are connectedto a conductive case. That is, instead of connecting unlike terminalsfrom each stack together to provide a series connection, the conductivecase is used to electrically connect the stacks of each compartmenttogether. In the example shown in FIG. 107B, the anode terminal ofcompartment 8020 a and the cathode terminal of compartment 8020 b arenot brought out external to the case. Instead, the conductors from theanode plates of compartment 8020 a and the cathode plates of compartment8020 b are both electrically connected to the case 8010 which provides aconductive path between the two stacks. As above, the inner surface ofeach compartment is made non-conductive so as to electrically isolatethe electrolyte from the case. An insulating coating may also be appliedto the exterior of the case in order to electrically isolate it from therest of the components in the implantable medical device housing. Avoltage applied across terminals 8037 a and 8038 b again then sees acapacitance equal to the desired series connection of the two stacks.

The same principles as described above apply to a capacitor with threeor more stacks packaged in a multi-compartment case. FIG. 108 showsanother embodiment in which the case 8010 has three compartments 8020 athrough 8020 c containing separate stacks 8030 a through 8030 c,respectively. The stacks in this embodiment are arranged horizontallyrather than vertically. The stacks can be electrically connected inseries in a manner similar to that described above. In the FIG., acathode terminal 8037 a from the stack in compartment 8020 a can beconnected to an anode terminal 8038 b from the stack in compartment 8020b, and a cathode terminal 8037 b from the stack in compartment 8020 bcan be connected to an anode terminal 8038 c from the stack incompartment 8020 c. A voltage applied across the anode terminal 8038 afrom the stack in compartment 8020 a and the cathode terminal 8037 cfrom the stack in compartment 8020 c then sees a capacitance equal tothe series connection of all three stacks.

FIG. 109 shows a flat aluminum electrolytic capacitor 8100 according toone embodiment of the present subject matter. Many details of capacitor8100 are similar to capacitor 8100 described above and will be omittedherein. Capacitor 8100 includes a case 8110 and a generic device 8120for preventing development of excessive pressure within case 8110. Case8110, which comprises aluminum and has a D-shape in this exampleembodiment, includes a planar top face 8112, a generally semicircular orarced back face 8114, and a substantially planar front face 8116. (Aplanar bottom face is not visible in this view.) Although the exampleembodiment places device 8120 on front face 8116, other embodimentsplace device 8120 on any one of the other faces. Thus, the subjectmatter is not limited to any particular placement of device 8120 on orwithin the case. Additionally, the subject matter is not limited to anyparticular case form or composition.

FIG. 110, for example, shows an example cylindrical aluminumelectrolytic capacitor 8200 which includes a case 8210 and a genericdevice 8220 for preventing development of excessive pressure within case8210. Case 8210, which comprises aluminum in this example embodiment,includes a tubular portion 8212, a top or header 8214, and a bottom8216. The example embodiment places device 8220 on tubular portion 8212,whereas other embodiments place device 8210 on any one of the otherportions, such as on header 8214 or within the case.

FIG. 111 shows a partial cross-section of an example capacitor caseportion 8300, which is not only conceptually representative of anyportion of case 8110 or 8210 in FIGS. 109 and 110, but also includes afirst example device 8320 for preventing development of excess pressurewithin case 8110 or 8210. Case portion 8300 includes an exterior surface8300 a and an opposing interior surface 8300 b. Interior surface 8300 bfaces, or confronts, components, such as one or more capacitor elementsor modules (not shown), within case 8110 or 8210. Conversely, exteriorsurface 8300 a faces away from the one or more capacitor elements.

Surfaces 8300 a and 8300 b define a case thickness 8300 t, measured in adimension generally perpendicular to at least one of the surfaces. Casethickness 8300 t in the example embodiment is less than 0.015 inches(0.381 millimeters.) Some embodiments use cases as thin as 0.005 inches(0.127 millimeters) or as thick as 0.025 inches (0.635 millimeters.)Other thicknesses are possible without departing from the scope of thepresent subject matter.

Device 8320 comprises an aperture or hole 8322 within case portion 8300,a membrane 8324 covering hole 8322, and adhesive layer 8326 adheringmembrane 8324 to case portion 8300. Hole 8322 extends from exteriorsurface 8300 a to interior surface 8300 b and has a length or depthequal to case thickness 8300 t. In the example embodiment, hole 8322 issubstantially circular and of uniform diameter, for example, 0.050inches (1.27 millimeters), for the full thickness of case portion 8300.Other embodiments provide linear or non-linear tapered holes withincreasing or decreasing diameter from the interior surface to theexterior surface of the case or dual tapered holes with a first portionof increasing diameter and a second portion of decreasing diameter.Still other embodiments also vary the shape and placement of the hole.The hole can be placed with awareness of the implant attitude of thecapacitor. Example hole-formation techniques include drilling, cutting,laser cutting, or etching. Thus, the subject matter is not limited toany particular hole geometries, dimensions, or placement.

Membrane 8324, which comprises a semi-permeable material, covers hole8322, controlling passage of fluids, that is, liquids and/or gases,through hole 8322. Membrane 8324 includes respective interior andexterior surfaces 8324 a and 8324 b.

In one embodiment, interior surface 8324 a abuts exterior surface 8300 aof case portion 8300. However, in other embodiments exterior surface8324 b abuts interior surface 8300 b, meaning that the membrane iswithin the case. Example materials for membrane 8324 include agas-permeable and liquid impermeable polytetrafluorethylene (PTFE)barrier. This material is permeable to hydrogen gas, which is generallyreleased during normal operation of wet aluminum electrolyticcapacitors. Other example membrane materials include silicones,polypropelenes, acetates, and polyester. Still other example materialsmay be found in Mark Porter, Handbook of Industrial Membrane Technology,Noyes Publications, 1990.

However, the present subject matter is not limited to any particularmembrane form, structure, or composition so long as it performs thedesired function of preventing excessive pressures within the capacitorcase. (As used herein, excessive pressures include, for example, anypressure level that is more likely than not to distort the shape of thecapacitor case and/or compromise the intended electrical characteristicsof the capacitor. Some cases are known to distort at a pressure of about15 pounds-per-square inch ) Thus, the scope of the present subjectmatter, for example, encompasses composite membranes, homogeneousmembranes, heterogeneous membranes, organic and inorganic membranes,symmetric and asymmetric membranes.

The example embodiment attaches the membrane to case portion 8300 usingadhesive 8326, such as epoxy, on one or more portions of the membrane.For example, the example embodiment places the adhesive at the interfacebetween exterior surface 8300 a of case portion 8300 and the peripheraledges of the membrane. Other embodiments place the adhesive in anannular region around hole 8322 between interior surface 8324 a of themembrane and exterior surface 8300 a of the case.

Additionally, other embodiments use other types of techniques to securethe membrane in place. Indeed, the membrane could be held in place witha strip of tape or by even wedging it between the capacitor case and anadjacent structure, such as relatively immovable wall or component, suchas another capacitor, within an implantable device.

FIG. 112 shows case portion 8300 with a second example device 8420 forpreventing development of excess pressure with case 8110 or 8210. Inthis embodiment, device 8420 includes a hole 8422 and a cylindrical plugor insert 8424 within hole 8422. Plug 8424, which is glued orcompression fit into hole 8422, includes a semi-permeable material likethat comprising membrane 8324 in FIG. 3. Although plug 8424 takes acylindrical shape in the example embodiment, it may take any shape orsize. Additionally, some embodiments extend a conductor, such as afeedthrough conductor, through plug 8424, allowing hole 8422 to serve asa feedthrough hole, as described above for FIGS. 67-69.

FIG. 113 shows capacitor case portion 8300 outfitted with a secondexample device 8520 for preventing development of excess pressure withincase 8110 or 8210. In this embodiment, device 8520 comprises a hole8522, and a spring-biased valve 8524 that controls passage of fluids,that is, liquids and/or gases, through hole 8522. Valve 8524 includes astand-off member 8524 a, a cantilever spring 8524 b, and a concave orhemispherical valve seat 8524 c. Stand-off member 8524 a lies adjacenthole 8522 and supports one end of cantilever spring 8524 b. The otherend of cantilever spring 8524 b extends over hole 8522, forcing concavevalve seat 8524 c, which is generally congruent in shape with hole 8522,to form a seal with the perimeter of the hole. (In some embodiments,valve seat 8524 c is composed of a rubber, such as EPDM (EthylenePropylene Diene Monomer) rubber, and in others it is composed of asemi-permeable material.) The seal opens with an interior pressure of,for example, 5, 10, or 15 pounds-per-square inch.

Although the present embodiment places valve 8524 on exterior surface8300 a, other embodiments may place the valve on interior surface 8300b. Other embodiments also use other valve assemblies. For example, someembodiments omit stand-off member 8524 a and attach an end of thecantilever spring directly to the exterior surface. Other embodimentsplace a valve at the end of tube or other fluid passage connected to thehole to allow greater flexibility in valve placement away from the case.Other embodiments may use electronic micro-machined valves actuated bythe charge-and-fire or therapeutic, circuitry of an implantable device.

FIG. 114 shows capacitor case portion 8300 outfitted with a thirdexample device 8620 for preventing development of excess pressure withincase 8110 or 8210. In this embodiment, device 8620 includes a hole 8622and an expandable bung 8624 that controls passage of fluids, that is,liquids and/or gases, through hole 8622. Expandable bung 8624 includes acylindrical plug portion 8624 a that has an interference or compressionfit with hole 8622, an axial passage 8624 b that extends through plugportion 8624 a, and an expandable (or inflatable) bladder portion 8624 cthat connects through passage 8624 b to the interior of capacitor case8110 or 8210. Bladder portion 8624 c includes an optional hole 8624 h.

The present embodiment forms expandable bung 8624 from an elasticmaterial such as a natural or synthetic rubber. However, otherembodiments use other materials such as polymers, flouropolymers, andother pliable synthetics.

In operation, bladder portion 8624 c expands as gases from the interiorof case 8110 or 8210 enter it through passage 8624 b to assume the formas 8624 c′, which approximates a 0.100-inch-radius sphere. The addedvolume of bladder portion 8624 c reduces the pressure in the capacitorcase. Hole 8624 h in the bladder allows gas to escape, thereby furtherreducing the pressure in the case. In one embodiment, hole 8624 h has adiameter or width smaller than that of axial passage 8624 b whichensures different fluid flow rates into and out of bladder portion 8624c. Among other advantages, one or more embodiments described aboveprovide devices for preventing excessive pressures from developingwithin the capacitor cases.

FIG. 115 shows one of the many applications for capacitors incorporatingone or more teachings of the present subject matter: an implantablemedical device or apparatus 9700. As used herein, this includes anyimplantable device for providing therapeutic stimulus to a heart muscle.Thus, for example, the term includes pacemakers, defibrillators,cardioverters, congestive heart failure devices, and combinations and/orpermutations thereof. Implantable medical device 9700 includes a leadsystem 9703, which after implantation electrically contact strategicportions of a patient's heart. Shown schematically are portions ofdevice 9700 including a monitoring circuit 9702 for monitoring heartactivity through one or more of the leads of lead system 9703, and atherapy circuit 9701 for delivering electrical energy through one ormore of the leads to a heart. Device 9700 also includes an energystorage component, which includes a battery 9704 and incorporates atleast one capacitor 9705 having one or more of the features of thecapacitors described above.

FIGS. 116A-116C illustrate a graph representing characteristics ofvarious embodiments of a capacitor, according to the present subjectmatter. The teachings of the present subject matter include a processfor producing a capacitor which exhibits the traits illustrated by thegraph. Among the various properties demonstrated by the graph arepractical limitations tied to various aspects of capacitor design.Overall, the graph is useful to illustrate aspects which aid inselection and development of improved capacitors.

The graph includes a three dimensional curve representing energydelivered in joules, voltage in volts, and volume in cubic centimeters.Depending on which aspects of the graph are analyzed, various trends areapparent.

For example, FIG. 116A demonstrates embodiments in which a capacitordelivers improved energy in the range of about 465V to about 565V. Thegraph illustrates both the relationship between voltage and energydelivered, and volume and energy delivered. From reading andunderstanding the graph, it is apparent that higher voltages enablehigher energy delivered, and that a higher capacitor volume enableshigher energy delivered. The particular shape of the curves, and theenergy delivered, are, in part, functions of the surface shape of thecapacitor. For example, embodiments including capacitors with increasedsurface area due to etching, which have a dielectric formed on thesurface area without substantial reduction in the surface area, providemore energy per volumetric unit. Additionally, embodiments which haveincreased dielectric thickness enable higher voltages, which also resultin higher available energy levels. The present subject matter revealsvarying preferential ranges considering these criteria.

For example, one embodiment of the present subject matter is adapted todeliver an electrical pulse at a voltage of between approximately 490volts and approximately 540 volts. Another embodiment is adapted todeliver an electrical pulse at approximately 515 volts. In someembodiments, a compromise is necessary to achieve the preferredperformance. For example, in embodiments where approximately 515 voltsis chosen as the operating voltage, an electrolyte which is unable towithstand higher voltages is used. In varying embodiments, anelectrolyte which is unable to operate at the peak of the voltages curveevident in the graph is chosen because of technology limitations andcost limitations. However, it is to be understood that the presentsubject matter encompasses embodiments which operate at the voltagesdemonstrated by the graph, and the examples included in these teachingsare provided solely for illustration, and are not exhaustive orexclusive.

Additionally, the present subject matter includes embodiment adapted todeliver from about 5.3 joules per cubic centimeter of capacitor stackvolume to about 6.3 joules per cubic centimeter of capacitor stackvolume. Also, the present subject matter teaches embodiments adapted todeliver from about 5.5 joules per cubic centimeter of capacitor stackvolume to about 6.1 joules per cubic centimeter of capacitor stackvolume. One embodiment is adapted to deliver about 5.8 joules per cubiccentimeter of capacitor stack.

FIG. 116B shows a top view of a graph representing various properties ofone capacitor embodiment of the present subject matter. The graphillustrates, in part, the relationship between voltage and energydelivered.

FIG. 116C includes a view of the graph which demonstrates therelationship, in part, between volume and energy delivered. In varyingembodiments, the graph teaches that volumetric energy density, measuredin joules per volt, increases when volume is minimized for a requiredenergy delivered.

Thus, by reading and understanding the information provided by thegraph, it is possible to produce a capacitor with an improved packagingdensity, including, in part, improved volumetric energy density.

As referenced in the discussion for FIGS. 106A-106F, portions of theelectrode are masked prior to etch, in various embodiments. FIG. 117illustrates one example of a mask applied to the electrode of thepresent subject matter. In varying embodiments, a mask is applied to oneor both sides of the electrode. For example, line 9802 defines a portionof an electrode shape which is punched from a sheet, in varyingembodiments of the present subject matter. Applied to the sheet are afirst mask 9804 and a second mask 9806. In varying embodiments,including the embodiment pictured, masked portions eclipse the eventualshape of the electrode, represented by electrode shape 9802.

For example, the sheet includes a first major surface which is visible,and a second major surface substantially parallel to the first which ishidden. In varying embodiments, a first pattern of mask 9804 is appliedto the first surface, and a second pattern of mask 9806 is applied tothe second surface.

In varying embodiments, the first pattern of mask 9804 and the secondpattern of mask 9806 are shaped differently. In one example, the firstand second patterns have different shapes, and cover varying areas ofthe sheet. For example, pattern 9804 covers a first area of electrodeshape 9802, and pattern 9806 covers a second area of electrode shape9802, and the first area covered by pattern 9804 of electrode shape 9802is larger than the second area covered by pattern 9806 of electrodeshape 9802.

It should be noted that in varying embodiments, the shape of pattern9804 and the shape of pattern 9806 are chosen to assist inmanufacturing. For example, in varying embodiments, electrode shape 9802is cut from a sheet of etched and anodized electrodes. When a singlesheet is populated with multiple electrodes, in varying embodiments, thechoice of shape for pattern 9804 and pattern 9806 can aid in associatedmanufacturing steps.

In varying embodiments, transition line 9808 is skew to transition line9810. Varying examples increase the bending stress at the transitionbetween etched foil and non-etched foil, and by positioning thetransition line 9808 and 9810 in varying configurations, the bendingstress of the electrode 9802 is more evenly distributed about the foil,which, in some embodiments, reduces instances of cracking and breaking.

FIGS. 118A-118F illustrate varying patterns of mask for application to afoil, according to various embodiments of the present subject matter. Invarying embodiments, the mask can populate the pattern 9804 or thepattern 9806 illustrated in FIG. 117. It should be noted that the line9902 described in varying examples is equivalent to the line 9808 ofpattern 9804, and line 9810 of pattern 9806.

FIG. 118A illustrates an example of a mask constructed out of a patternof rounded square shapes arranged proximal to each other. In varyingembodiments, the shapes cover approximately 80% of the surface ontowhich they are printed, proximal the line 9902. Line 9902 defines, andthe area proximal the line, define a grade between masked electrode andnon-masked electrode. By angling the line 9902 in relation to otherlines which define the mask, the pattern includes a varied interface atline 9902. The pattern at line 9902 resembles a set of steps.

Through the angle at line 9902, the pattern reduces instances ofelectrode breakage proximal to the grade. For example, in someembodiments, the electrode is etched and exhibits undercutting at theborder between a masked portion and a non-masked portion. Parallel tothis border is an axis which approximately bisects the undercut.Undercutting, in varying embodiments, results in a portion of theelectrode which is weak while bending along the axis which bisects thelength of the undercut. However, in varying embodiments, the undercutportion of the electrode is strong when bending orthogonal to an axisbisecting the length of the undercut. Thus, undercutting increasesbending stress more in certain directions. By arranging the maskingpatter in the manner illustrated, the undercut portions of the electrodecan be controlled to improve the flexibility of the electrode whichreduces instances of breaking or cracking.

FIG. 118B illustrates an example of a mask constructed out of a patternof rounded squares arranged proximal to each other. In varyingembodiments, line 9902 defines an area across which elongate shapesspan. Various examples are shaped like a square wave. It is apparentupon reading and understanding these teachings that the elongate shapescan be constructed out of rounded blocks, and that the elongate shapescan be defined otherwise.

In varying embodiments, the mask includes exposed area 9908. In oneexample, exposed area 9908 is sized such that undercutting at theexposed area 9908 during etch does not substantially weaken theelectrode under bending stress.

FIG. 118C illustrates one example of a halftone suitable forstrengthening an electrode at the juncture between a masked portion andan unmasked portion. In one embodiment, the half tone is comprised ofsmaller rounded blocks 9904, and larger rounded blocks 9906. In oneembodiment, the reach of the halftone is defined by a line 9902, and islimited to a grade proximal to the line 9902. In additional embodiments,the halftone is not defined as such.

In varying embodiments, the halftone transitions from coveringapproximately 100% of the electrode at the masked grade, to coveringapproximately 0% of the electrode at the masked grade. In someembodiments, the halftone transitions from covering approximately 80% ofthe electrode at the masked grade, to covering approximately 60% of theelectrode at the masked grade. In varying embodiments, this can beaccomplished with rounded blocks placed proximal to each other, and inadditional embodiments, it is accomplished with other shapes arranged ina predictable pattern, such as a grid, or in a random pattern.

FIG. 118D illustrates an example of a halftone suitable forstrengthening an electrode at the junction between a masked portion andan unmasked portion.

FIG. 118E illustrates an example of a pattern useful for strengtheningan electrode in the region of a transition from a masked area to anunmasked area, according to various embodiments of the present subjectmatter. By including a sinusoidal shape which spans the line 9902, theinstances of undercutting which are parallel to the bending line (thebending line is approximately parallel to transition line 9902) areminimized.

FIG. 118F illustrates a pattern for strengthening an electrode in anarea where undercutting is put in bending stress, according to variousembodiments of the present subject matter. In varying embodiments, thepattern is comprised of elongate shapes 9910. In varying embodiments,the elongate shapes demonstrate an improved resistance to cracking andbreaking when the etched foil is subjected to bending stresses which areproximal the transition line 9902.

FIG. 119 shows a process for producing a foil 9950 with a partiallyetched area, according to various embodiments of the present subjectmatter. In varying examples, the process includes depositing a curableresin mask onto a foil 9952. For example, in one embodiment, the mask isdeposited on a foil using a computer controlled mask dispensing system.In one example, ink is deposited using an ink-jet process.

The control systems shown and described here can be implemented usingsoftware, hardware, and combinations of software and hardware. As such,the term “system” is intended to encompass software implementations,hardware implementations, and software and hardware implementations.

In various embodiments, the methods provided above are implemented as acomputer data signal embodied in a carrier wave or propagated signal,that represents a sequence of instructions which, when executed by aprocessor, cause the processor to perform the respective method. Invarious embodiments, methods provided above are implemented as a set ofinstructions contained on a computer-accessible medium capable ofdirecting a processor to perform the respective method. In variousembodiments, the medium is a magnetic medium, an electronic medium, oran optical medium.

Additional embodiments cure the mask onto the foil 9954. Examples ofcurable resin mask include ink, and photoresist. In varying embodiments,the curable resin mask is cured to the foil. For example, in oneembodiment, ink is deposited on the foil, and then is baked to the foilin an oven. Baking, in some embodiments, exposes the curable resin maskto radiant heat energy, which can increase hardness or the curable resinmask, and which also can decrease the time needed for curing. In varyingembodiments, the oven is adapted to cure the curable resin mask withoutaffecting the foil otherwise.

In varying embodiments, the foil is etched 9956, and the mask protectsthe foil from the etchant. Etching, in varying embodiments, is describedin the discussion associated with FIG. 17, but in other embodiments,variations of the etching process are used.

Varying examples of the process then remove the mask 9958. Removing themask, in one embodiment, includes submerging the foil with mask in asolution adapted to dissolve the mask.

Some embodiments anodize the foil 9960. Anodization, in one embodiment,is accomplished by the process discussed in the teachings associatedwith FIG. 17. However, these teachings should not be understood to beexhaustive or exclusive, and other methods of forming a dielectric on afoil are within the scope of the present subject matter. Additionally,it should be noted that other examples anodize the foil while the maskis in place.

Varying embodiments cut the anodized foil into shapes 9962, and in someexamples, the foil shapes are then assembled into a capacitor 9964.

FIGS. 120-125 show various views of example embodiments of the presentsubject matter. Although the various views include matching numbers tohelp in explanation, these matching numbers should not be read aslimiting. Embodiments with variations not enumerated in the text orillustrations associated with FIGS. 120-125 are within the scope of thepresent subject matter, and these examples should not be interpreted asexhaustive or exclusive of the present subject matter.

FIG. 120 shows a flat capacitor 10100, according to one embodiment ofthe present subject matter. Capacitors must include at least one anodeelement and at least one cathode element, but are not constrained to oneshape by design. Capacitors which are substantially planar, in variousembodiments, offer a geometry which is beneficial for packaging.Substantially planar capacitors offer additional benefits as well, suchas improved performance and manufacturing efficiency. It should benoted, however, that although capacitor 10100 is D-shaped andsubstantially planar, in varying embodiments, the capacitor is shapeddifferently, including other symmetrical or asymmetrical shapes.

Capacitor 10100 includes a case, which in some embodiments includes atleast two components; a substantially flat surface and connectedsidewalls which form a cup-shaped receptacle, and a substantially flatcover. In various embodiments, the case has one or more openings, andthe cover conforms to one of the openings. In one embodiment, the coveris located approximately parallel to substantially planar surface 10102.In one embodiment, the case 10114 includes a curvature 10116 whichallows the case to be placed in receptacles which conform to thecurvature. Among other benefits, the case is useful to retainelectrolyte in capacitors using a fluidic electrolyte. In other words,various examples of the present subject matter comprise flat capacitorswith a number of electrodes stacked and placed in a case, with the casefilled with electrolyte.

It should be noted that in various embodiments, the case and coverinclude openings which are formed, in part, by features present in oneor both the cover and the case. For example, in one embodiment, thecup-shaped receptacle includes a semi-circle shaped edge discontinuity,and the cover includes a semi-circle edge discontinuity, and when theyare assembled, they form a circle shaped opening in a case.

In accordance with the design requirement of retaining electrolyte, invarious examples, the case and the cover mate to form a seal. Varyingembodiments use welding to join the case and the cover. For example, inone embodiment, the cover is laser welded to the case 10114. In oneembodiment, the weld is performed by an approximately 1064 nm Yag laserweld with an energy range of approximately 2.5 joules to 3.5 joules.Other embodiments use mechanical locks to join the cover and case, orvarious forms of adhesive. Some embodiments use a combination of knownjoining methods, including crimping combined with welding. Preferreddesigns form a seal between the case and the cover which resists theflow of electrolyte.

In various embodiments, the capacitor of the present invention includesan anode conductor 10104 and a cathode conductor 10106. In variousembodiments, these conductors connect the anode of the capacitor stackand the cathode of the capacitor stack with electronics which arelocated external to the capacitor. In various embodiments, one or bothof these conductors are electrically isolated from the capacitor case.In one example, the case 10114 of the capacitor is electricallyconductive and comprises a portion of the cathode. This example variantis manufactured from aluminum, and connected to the cathode of thecapacitor stack using a connection means internal to the case 10114. Inother embodiments, the case is manufactured using a nonconductivematerial, such as a ceramic or a plastic. It should be noted that thecase can also comprise a portion of the anode.

In embodiments where the capacitor case forms part of a set of capacitorelectrodes, one way to economically connect a conductor to the desiredportions of the capacitor stack is to connect the conductor directly tothe exterior of the case. In various embodiments, attaching an electrodeto the case is facilitated by a plate. One example uses a plate 10110which is electrically conductive, and which is laser welded to the case10114, placing the plate 10110 in electrical communication with the case10114. In one embodiment, the weld is performed by an approximately 1064nm Yag laser weld with an energy range of approximately 1.5 joules to2.5 joules. The seal formed by welding a plate to a case, in variousembodiments, is sufficient to restrict the flow of electrolyte. In oneexample, cathode conductor 10106 is arc percussion welded to the plate10110. The result of this process is that the conductor is placed inelectrical communication with the capacitor stack located inside thecase. In other words, in one embodiment, the cathode conductor 10106 ispercussion welded to the plate 10110, which is laser welded to the case10114, which is in electrical communication with the cathode of thecapacitor stack placed inside the case 10114.

Additionally, in various examples, the plate includes an aperture sealedby a plug. In one example, a plug 10108 is laser welded to the plate10110. In one embodiment, the weld is performed by an approximately 1064nm Yag laser weld with an energy range of approximately 1.5 joules to2.5 joules. In varying embodiments, the plug and aperture are used tofill the capacitor case with electrolyte. The seal formed by welding theplug to the plate is, in some examples, sufficient to restrict the flowof electrolyte.

Varying embodiments of the present subject matter include a conductorfeedthrough in the case. In various embodiments, a feedthrough enables aconductor to provide a conductive path from the exterior of the case tothe interior of the case without conducting electricity to the case. Anexample embodiment includes a cathodic case 10114 and uses a feedthroughto put the anode of the capacitor stack in electrical communication withelectronics external to the case 10114, in a manner isolated from thecathodic case. The example uses the anode conductor 10104, which passesthrough the feedthrough, to conduct electricity. Because the feedthroughpassageway comprises a hole in the case, in embodiments where thecapacitor is filled with electrolyte, the feedthrough passageway must besealed. To seal the feedthrough passage, various examples include acurable resin disposed between the case and the conductor, the curableresin conforming to the feedthrough passage, and resisting the flow ofelectrolyte. In one example, the curable resin 10112 is an epoxyconforming to the feedthrough passageway and bonded to the anodeconductor 10104 and the case 10114. Varying embodiments form a hermeticseal.

Overall, the present subject matter enables various improvements overthe current art. For example, by eliminating the need to pass one ormore conductors through the case by directly connecting the conductor tothe plate, the cost of capacitor manufacturing can be reduced, andcomplexity affecting reliability and manufacturing can be reduced. Byusing a plate, a capacitor design can include a case of varyingthicknesses. In one embodiment, the thickness of the insert plate is0.030 inches. In varying embodiments, insert plates run fromapproximately 0.020 inches thick to 0.040 inches thick. In varyingembodiments, the insert plate is combined with a case this isapproximately 0.010 inches thick. Additionally, in one embodiments, acase which is from about 0.008 inches thick to about 0.015 inches thick.

For example, in one embodiment, the plate mounts coplanar to theexterior of the case, but extends into the capacitor deeper than doesthe thickness of the case 10114. One benefit of this design is that awelding process for connecting a conductor to the case may be used whichrequires material thickness greater than that of the case 10114. Forexample, one embodiment uses arc percussion welding with parameterswhich are sufficient to weld a conductor to the plate 10110, but whichwould damage the case 10114 if the conductor were welded to the case10114. In other words, the present subject matter allows using acapacitor with a case which is too thin for some metal bondingprocesses, but which is otherwise sufficient to satisfy otherrequirements of the case, such as retaining electrolyte and a capacitorstack. This design, in various embodiments, allows for a reduction incase thickness and mass, without sacrificing welding options availablefor connecting the conductor to the capacitor, ultimately providing fora smaller capacitor, and therefore, for a smaller implantable device.

FIG. 121 illustrates a close up view 10200 of the plate and plug of FIG.120, according to one embodiment of the present subject matter. Invarious embodiments, the capacitor includes case 10114. In oneembodiment, the case includes a curvature 10116 which is adapted toallow the capacitor to be placed in a similarly shaped receptacle. Theexample also includes a cathode conductor 10106, an anode conductor10104, a curable resin 10112, a plate 10110, and a plug 10108.Additionally, various embodiments include an aperture which extends fromthe exterior of the case to the interior of the case, and which, in someexamples, passes through the plate.

In one example embodiment, plate 10110 is welded to case 10114 forming aseal which restricts the flow of electrolyte. Similarly, the aperture10414 is sealed and resists the flow of electrolyte by welding the plug10108 to the plate 10110, in various embodiments of the present subjectmatter. It should be noted that in other embodiments of the presentsubject matter, the plate is fastened to the case with other fasteningmeans, including a physical lock such as threads. Additionally, the plug10108 is fastened to the plate with alternate fastening means, such asthreads. These and other types of fastening designs are within the scopeof the present subject matter, and the list enumerated here is notintended to be limiting.

FIG. 122 illustrates an exploded view of a capacitor 10100, according toone embodiment of the present subject matter. In various embodiments,cup shaped receptacle 10314 includes a feedthrough passageway 10308which is formed in a sidewall of the cup shaped receptacle 10314.Additionally, a cover 10204 is adapted for conforming to an opening inthe cup shaped receptacle 10314 of the case 10114 (illustrated in theexample FIG. 121, in one embodiment). The feedthrough passageway 10308,in various embodiments, is useful to allow the passage of a conductorwhich connects external circuitry at one end to a capacitor stack at theother. Additionally, in various embodiments, a paper isolating element10306 is placed proximal to the feedthrough passageway 10308, andinternal to the case. For example, in one embodiment, the anodeconductor 10104 passes through the case and connects to the anode of thecapacitor stack 10302. In some embodiments, case 10114 includes two ormore feedthrough passageways.

In various embodiments, extending through feedthrough passageway 10308is anode conductor 10104. This conductor, in various embodiments, isadapted to connect to anode connection surface 10310. Anode connectionsurface 10310, in various embodiments, is comprised of a plurality ofanode layers welded together, but other variations, including singleanodes or multiple anodes are within the scope of the present subjectmatter. For example, in one embodiment, anode conductor 10104 and theplurality of anodes are put into electrical connection through joiningthe plurality of anodes to the anode conductor 10104.

Internal to various embodiments of the assembled capacitor is a terminal10304. In various embodiments, the terminal 10304 is for connection to acathode connection surface 10312. Cathode connection surface 10312, invarious embodiments, is comprised of a plurality of cathode layerswelded together, but other variations, including single cathodes ormultiple cathodes are within the scope of the present subject matter.For example, in one embodiment, cathode conductor 10104 and theplurality of cathodes are put into electrical connection through joiningthe plurality of cathodes to the cathode conductor 10104.

Various embodiments include terminal 10304 connected to capacitor stack10302 using cathode connection surface 10304 and to one of the groupincluding the cup shaped receptacle 10314, the cover 10204, or both thecup shaped receptacle 10314 and the cover 10204. In various embodiments,a connection between the terminal 10304 and the cover 10204 is formed bypinching the terminal 10304 during assembly of the capacitor stack10302, the cup-shaped receptacle 10314, and the cover 10204. Variousembodiments connect terminal 10314 to the electrode stack 10302 usingadditional means, such as welding.

In one example, the cathode conductor 10106 is connected to the plate10110, which is connected to the cup shaped receptacle, which isconnected to terminal 10304, which is connected to the cathode of thecapacitor stack 10302. Additionally, a plug 10108 is attached to theplate 10110.

The capacitor stack 10302, in various embodiments, is constructed in ashape which approximates the interior space in the receptacle, in orderto reduce unused space, which can reduce capacitor size, andconcomitantly, device size. One method of reducing device size includeschoosing components in the capacitor stack to adjust the physicaldimensions of the capacitor stack 10302. For example, in one embodiment,anode layers are added or subtracted from the stack, resulting in acapacitor stack 10302 which matches the interior volume of a particularcase. In this example embodiment, the capacitor stack includes 20cathode layers, and 58 anode layers, but it should be understood thatother embodiments include different numbers of elements.

FIG. 123A illustrates the front view of a plate 10110, according to oneembodiment of the present subject matter. In various embodiments, theplate 10110 includes an aperture 10414. Some embodiments include anaperture 10414 with a first portion 10202, and a second portion 10206.Various embodiments of the first portion 10202 and the second portion10206 comprise coaxial cylindrical shapes with varying diameters.Additionally, various embodiments of the plate include a first majorsurface 10410.

In various embodiments, the plate 10110 is shaped like an irregularpentagon with three rounded adjacent apexes which are approximately 90degrees, and two rounded adjacent apexes which are obtuse angles.However, it should be noted that other plate shapes are within the scopeof the present subject matter.

FIG. 123B illustrates a cross section of a side view of a plate 10110,according to one embodiment of the present subject matter. The view cutsthe plate 10110 through the aperture 10414. In various embodiments, theaperture 10414 includes a first portion 10202. Various examples of theaperture 10414 are shaped like a counterbore, with the first portion10202 comprising a larger diameter, the second portion comprising asmaller diameter, and the difference between the two diameterscomprising a substantially planar step shape defined by the concentriccircles of the perimeters of the first and second portions. In variousembodiments, the first portion 10202 opens to the first major surface10410. In additional embodiments, the first portion 10202 has a depth oft1, and the second portion 10206 has a depth which is the distance ofthe depth t1 subtracted from the thickness of the plate 10110.

In various embodiments, the aperture is adapted to mate with a plug, asis demonstrated by the plate 10110 and the plug 10108 of the exampleillustration of FIG. 121. In various embodiments, the plug 10108 roughlymatches the shape defined by the first portion 10202 of the aperture10414. In embodiments using the plug to form a seal with the aperture, aplug is selected which includes a thickness which is approximately equalto the thickness t1. In various embodiments, the surface of the plug isroughly coplanar with the surface of the plate once installed. Variousexamples of the present subject matter affix the plug to the plate 10110using welding, an interference fit, adhesive, threads, or variousadditional forms of attachment. On embodiment uses laser welding. In oneembodiment, the weld is performed by an approximately 1064 nm Yag laserweld with an energy range of approximately 1.5 joules to 2.5 joules. Invarious embodiments, the plate is adapted to mate with an opening in acase 10114, as illustrated in the example of FIG. 120. For instance, inone embodiment, the plate is shaped to restrict its passage through anopening in the case 10114. Accordingly, one example of the plateincludes a step 10402 which divides the plate into a first section witha first major surface 10410, and a second section with a second majorsurface 10412. In one embodiment, the first major section 10410 is sizedfor passage through an opening in a case 10114, and the second majorsection is sized so that it cannot pass through the same opening. In oneembodiment, the face of the step 10402 is positioned proximal to aninterior surface of case 10114, and is further positioned proximal to anopening in the case 10114.

In various embodiments, the plate includes a thickness t2. In variousembodiments, the thickness t2 is selected to match the thickness of acapacitor case, including the case illustrated in the example of FIG.120. In examples where t2 matches the thickness of a capacitor case, themajor face 10110 is coplanar with the exterior of a capacitor case whenthe plate 10110 is attached to the capacitor case. It should be notedthat the relationship between t1 and t2 is not intended to be exhaustiveor exclusive, and it provided solely for illustration.

Generally, the thickness of the plate 10110 depends on the type andnature of the contents of the capacitor. In general, a thickness ischosen which is compatible with desired manufacturing processes. Forexample, in embodiments where a conductor is welded to the plate 10110,a plate thickness is chosen which will result in a final plate shape,after welding, which is substantially similar to the shape of the plateprior to the welding process. In other words, in various embodiments,the thickness of the plate is selected to minimize warpage due tothermal stress applied to the plate 10110 due to various processes,including welding.

In general, the plate can be manufactured by machining, powderedmetallurgy, or by stamping. Additional forming processes are also withinthe scope of the present subject matter. In various embodiments, thetransition between the first portion 10202 of the aperture and thesecond portion of the aperture 10206 is designed with the objective ofenabling laser welding. In some examples, enabling a laser weld requiresthat the transition include step shapes which are largely perpendicular.Varying embodiments of a laser welding process require a step shape tolimit laser energy from extending beyond the welding area.

FIG. 124 shows a side view of conductor 10106 attached to a plate 10110with a first major face 10410, according to one embodiment of thepresent subject matter. In various embodiments, the conductor 10106includes a wire 10510 and a coupling member 10512, and one or more arcpercussion welding areas, 10506, 10508, 10502 and 10504. In variousembodiments, the wire 10510 is attached to the coupling member 10512using a crimping process, a welding process, or other processes. In oneembodiment, the coupling member 10512 is arc percussion welded to thewire at one or more areas. In various examples, areas 10506 and 10508are used for applying an arc-percussion weld. Additionally, the couplingmember 10512 is arc-percussion welded to a plate 10110 in variousembodiments, and in one embodiment the coupling member 10512 is arcpercussion welded at areas 10502 and 10504. Because of the nature of arcpercussion welding, the mating region between the plate 10110 and thecoupling member 10512 must be chosen to enable a desired form of weld.In one example, coupling member 10512 and plate 10110 includesubstantially planar faces which are adapted to mate with each other.

An example arc percussion welding machine is manufactured by Morrow TechIndustries of Broomfield, Colo. In this embodiment, the conductor 510and coupling members are not crimped together. However, some embodimentsinclude both welding and crimping.

It should be noted that in some embodiments, the wire 10510 and thecoupling member are one piece. Additionally, it should be noted thatother forms of conductor 10106 which are adapted for percussion weldingto a plate 10110 are within the scope of the present subject matter.

FIG. 125 shows a cross-sectional side view of details of one embodimentof feedthrough assembly 10620. In some examples, a means is availablefor connecting the capacitor stack contained in the case to electronicswhich are located outside of the case. In some of these embodiments, theconnecting means is of one polarity, and the capacitor case is ofanother polarity. In these embodiments, it is necessary to provide astructure for allowing electricity to pass through the case wall withoutcontacting the case wall. In various embodiments, the feedthroughassembly 10620 provides one embodiment adapted for providing this. Invarying examples, the feedthrough assembly 10620 includes a feedthroughpassageway 10308 which is drilled, molded, punched, or otherwise formedin a portion of a sidewall of the case 10114. Additionally, in someembodiments, the feedthrough passageway is located in a plate, or islocated partially in a case and partially in a plate. For example, inone embodiment, one half of a feedthrough passageway is located in aplate or cover and one half of a feedthrough passageway is located in acase.

In some embodiments, the feedthrough assembly 10620 includes an anodeconductor 10104 which is attached to the anode of the capacitor. Varyingembodiments of the capacitor anode include one or more anode members10608 which are coupled to anode conductor 10104 for electricallyconnecting the anode to circuitry outside the case 10114. In oneembodiment, anode members 10608 are edge-welded to each other.Edge-welding the anode members 10608, in various embodiments, provides aflat connection surface 10410. In some embodiments, anode members 10608are crimped or soldered, and in further embodiments, the anode members10608 are connected by an electrically conductive adhesive or by othermeans.

In some embodiments, a wire 10604 is coupled to a coupling member 10606,forming, in part, an anode conductor 10104. Various embodiments of thepresent subject matter include attaching the wire 10604 to the couplingmember 10606 using soldering, welding, crimping, and other methodssufficient to connect the wire 10604 to the coupling member 10606, invarying embodiments. In one embodiment, anode conductor 10104 is asingle, substantially unified metallic crystalline member.

In one embodiment, coupling member 10606 is a high-purity aluminummember which is able to withstand the high voltages generated within thecapacitor case. In other embodiments it is made from another conductivematerial compatible with the capacitor stack 10302 (illustrated inexample FIG. 122 in one embodiment). In various embodiments, one side ofthe coupling member 10606 includes a planar surface for attaching to theplanar surface 10610 presented by edge-welded capacitor stack 10608.

In one embodiment, coupling member 10606 is laser welded to surface10610 of capacitor stack 10302 using a butt-weld. Alternatively,coupling member 10606 is attached using other means. Butt-weldingcoupling member 10606 directly to capacitor stack 10302 provides anelectrical connection between capacitor stack 10302 and the conductor.Also, since coupling member 10606 is directly attached to capacitorstack 10302, it supports the conductor while a curable resin 10112, suchas an epoxy, is applied to the feedthrough passageway area.

In one embodiment, feedthrough passageway 10308 is in part defined by anedge which is tapered to improve the surface area available to a bondingagent. Curable resins bond to surfaces, and as such, can create a largerbonding areas when applied to a larger surface area. A larger bond, invarious embodiments, is more robust, reliable, and is less likely topermit leaks. Additionally, in one embodiment, a larger bonding area canincrease the distance between the coupling member and the case byincluding a larger feedthrough passage. Accordingly, increased area canreduce instances of unwanted arcing. A tapered edge, in variousembodiments, includes these benefits.

For example, in one embodiment, a feedthrough passageway includes aninbound narrowing sidewall 10624 extending to a lip 10622. In variousembodiments, a cavity is defined by the sidewall 10624, the couplingmember 10606, and an isolating element 10306. A curable resin 10112, invarious embodiments, is disposed in the cavity and hardened, and servesto insulate the case 10114 from the anode conductor 10104, and furtherserves as a seal to resist the flow of electrolyte 10602. For example,in one embodiment, the conductor is an uninsulated anode conductor 10104connected to the anode of the capacitor stack, the anode conductor 10104passing through a feedthrough passageway 10308 in a cathodic case 10114.In this example embodiment, a curable resin 10112 is used to sealelectrolyte 10602 into the capacitor, and is further used to insulatethe anodic elements, such as the coupling 10606, from the cathodicelements, such as the case 10114. In one example, the curable resin10112 is a hardened two-part quick-setting thermal-set epoxy.

In one embodiment, an isolating element 10306 is combined with theconductor 10104, the feedthrough passageway 10308, and the curable resin10112. This combination, in various embodiments, in useful forrestricting the flow of electrolyte 10602, curable resin 10112, or both.In various embodiments, the isolating element 10306 is a paper washerwhich assists in limiting the flow of curable resin 10112 to a desiredarea. One benefit of using an isolating element 10306 to restrict theflow of a curable resin, such as epoxy, is that the epoxy is less likelyto flow into other locations within the capacitor, which can adverselyaffect capacitor performance.

In varying embodiments, the feedthrough passageway 10308 is assembled tothe capacitor stack and seals to the capacitor stack surface 10610, andin additional embodiments, the feedthrough passageway 10308 seals to thecoupling member 10606. In one embodiment, the feedthrough passageway10308 includes a lip 10622 adapted for forming a circular seal with thecoupling member 10606. In various embodiments, because of the nature ofassembly, including imperfect manufacturing tolerances and imperfectsurface finishes, the effectiveness of the seal formed between thefeedthrough passageway 308 and the coupling member 10606 is limited. Toincrease the effectiveness of the seal, in various embodiments, anisolating element 306 is located between the feedthrough passageway10308 and the coupling member 10606 which is compressible, and whichresists the flow of electrolyte and resists the flow of epoxy. In oneembodiment, the isolating element 10306 is constructed from paper whichis of a thickness which can absorb manufacturing irregularities, such assurface finish irregularities and manufacturing toleranceirregularities, while providing a seal.

In additional embodiments, the isolating element 10306 is useful forproviding electrical insulation between the case 10114 and the anodeconductor 10104. In one embodiment, the isolating element is made fromseparator paper. For example, in various embodiments, the case iscathodic, and an anodic coupling 10606 must be electrically isolatedfrom the case 10114 for the capacitor to function. Additionally, invarious embodiments, to reduce the size of the capacitor, the anodeconductor 10104 and the case 10114 are placed near one another.Therefore, in various embodiments, to reduce instances of arc betweenthe case and the anodic conductor 10104, an insulative element 10306 isdisposed between the case 10114 and the anode conductor 10104.

In various embodiments, a curable resin 10112 is any of numerous clearto translucent yellow or brown, solid or semisolid, viscous substancesof plant origin, such as copal, rosin, and amber, used principally inlacquers, varnishes, inks, adhesives, synthetic plastics, andpharmaceuticals. Additionally, curable resin 10112 includes any ofnumerous physically similar polymerized synthetics or chemicallymodified natural resins including thermoplastic materials such aspolyvinyl, polystyrene, and polyethylene and thermosetting materialssuch as polyesters, epoxies, and silicones that are used with fillers,stabilizers, pigments, and other components to form plastics. It shouldbe noted that the sealing members listed here are not a complete list ofthe sealing members within the scope of the present subject matter. Forexample, various examples include sealing members which provide anon-hermetic seal, and one embodiment includes a substantially elasticplug.

It should be noted that the embodiments enumerated here, in which ananode conductor passes through a feedthrough assembly, are only examplesof the present subject matter. Additional embodiments include a cathodeconductor passing through a passageway in an anodic capacitor case.Further, additional embodiments include multiple feedthrough passages,and some include a case which is neither anodic nor cathodic.

FIG. 126 shows a method 10700 for manufacturing an implantablecardioverter defibrillator according to one embodiment of the presentsubject matter. In various embodiments, the method includes providing acapacitor receptacle with at least two openings 10702. For example,various embodiments include a cup-shaped receptacle, with a majorsurface and side-walls extending from the surface and forming adish-shaped volume. In one embodiment, the receptacle side-walls includetwo openings: a first opening which is adapted for mating with a plate,and a second opening which is adapted for mating with a cover. Invarious embodiments, the receptacle is a conductive metal, and in oneembodiment, the receptacle is aluminum.

In various embodiments, the method includes attaching a plate to one ofthe openings in the receptacle 10704. In various examples, the plate issized for mating with the first opening. In some examples, the plate issubstantially planar, and cannot pass through the first opening whenpositioned approximately parallel to the sidewall which includes theopening. Additionally, in various embodiments, the plate is sizedthicker than the sidewall of the receptacle. In embodiments where thesidewall is not of a uniform thickness, the plate is thicker than atleast part of the sidewall proximal to the opening to which the plate isattached.

Varying embodiments attach the plate using a welding process. In oneembodiment, the plate is attached using a laser welding process. Inother embodiments, the plate is attached to the receptacle using othermeans, such as threads or a mechanical lock. In various forms, attachingthe plate to the receptacle forms a seal, and in some embodiments theseal resists the flow of electrolyte.

Various embodiments of the present subject matter include a plateadapted for attachment of a terminal. Various embodiments includeattaching a terminal to the plate 10706. For example, in variousembodiments, a terminal is welded to the plate. In one embodiment, aterminal is percussion welded to the plate. In various embodiments, theparameters of the percussion weld require a plate of a minimumthickness, and the plate is sized to approximate that thickness. Bysizing the plate to approximately match the required parameters of thewelding process, only a portion of the capacitor case is produced atthat thickness, allowing the remaining portions, which are not weldedto, to be thicker or thinner. In one embodiment, a thinner receptacle isused, which results, in various embodiments, in a capacitor which issmaller and lighter.

In various examples, a capacitor stack is placed in the capacitorreceptacle through the second opening 10708. Additionally, variousembodiments include attaching a cover to the second opening 10710.Attaching the cover includes, in various embodiments, includes weldingthe cover to the receptacle. In one embodiment, a seal is created usinga laser welding process which resists the flow of electrolyte.

Various embodiments also include filling the receptacle with electrolyte10712, and sealing the receptacle to resist the flow of electrolyte10714. For example, in one embodiment, an aperture provides access tothe interior volume formed by attaching the plate and the cover to thereceptacle. In various embodiments, the aperture is the only access tothe interior of the capacitor case which does not resist the flow ofelectrolyte. In various embodiments, the method of the present subjectmatter includes filling the volume with electrolyte. For example, invarious embodiments, the volume is filled, and later pressurized toencourage the escape of gasses from the interior volume of thecapacitor. In one embodiment, the gases escape through the aperture.Various embodiments include sealing the aperture after the capacitor hasbeen filled with electrolyte to resist the flow of electrolyte.

FIG. 127 shows a method 10800 for manufacturing an implantablecardioverter defibrillator, according to one embodiment of the presentsubject matter. For example, in various embodiments, a receptacle isprovided with a first opening and a second opening 10802. In someembodiments, a plate is inserted 10804 into the receptacle and attached10806 to the first opening. In one embodiment, the plate issubstantially planar and is sized so that it cannot pass through thefirst opening when positioned approximately parallel to the plate formedby the perimeter of the opening.

In various embodiments, the plate includes an aperture. In oneembodiment, the plate is inserted and attached to the receptacle, acapacitor stack is installed in the receptacle 10808, and a cover isattached to the receptacle 10810. The example embodiment is assembledforming a seal which resists the flow of electrolyte, excluding theaperture. Various examples which are sealed to resist the flow ofelectrolyte are filled with electrolyte 10812, which substantiallyimpregnates the interior volume of the capacitor case. Various examplesuse a pressure differential to encourage the impregnation of theinterior volume of the capacitor with electrolyte.

Various examples plug the aperture with a member 10814, which can beattached in a number of ways, including welding, interference fit,threading, and other means suitable for forming a sealed attachment. Inone embodiment, the aperture is sealed by laser welding a disc shapedplug into a similarly shaped counterbore in the aperture.

FIG. 128 shows a method 10900 for manufacturing an implantablecardioverter defibrillator according to one embodiment of the presentsubject matter. In various embodiments, the method of the presentsubject matter includes assembling a stack with at least one terminal10902. In various embodiments, a paper isolating element 306 isassembled to the terminal 10904. In one example embodiment of thepresent subject matter a paper washer is inserted onto a terminal whichis shaped like a boss.

In various embodiments, the assembled capacitor stack is placed into areceptacle with a first opening and a second opening 10906. Variousexamples of the method of the present subject matter include aligningthe terminal with the first receptacle opening. One example includesaligning the terminal with the first receptacle opening so that theterminal passes at least part of the way through the receptacle opening.

Various embodiments attach a cover to the second receptacle opening10909. Various embodiments include attaching the cover using a weldingprocess, including laser welding. Additional embodiments includeattaching the cover with various additional methods, including usingmechanical locks, rivets, fasteners, or other forms of fasteningmethods. In various embodiments, attaching the cover to the secondreceptacle opening includes forming a seal between the cover and thereceptacle. In one example, the seal is adapted for resisting the flowof electrolyte.

In various embodiments, a sealing member is used to seal the terminal tothe first opening 10910. For example, in various embodiments, an epoxyis used to seal the space between the terminal and the first opening. Inone example embodiment of the present subject matter the paper isolatingelement 10306 is adapted to interface with the first opening and theterminal to form a seal which is adapted to localize the epoxy proximalto the interface between the paper insert, the terminal, and the secondopening. In other words, the paper isolating element 10306 is adapted tolimit the epoxy to wetting proximal to the terminal, the first opening,and the paper insert.

It should be noted that the methods of the present subject matter, invarious embodiments, include inserting the assembled capacitor into animplantable medical device suited for delivering electrical stimulationto a patient. In one embodiment, the method of the present subjectmatter includes installing a capacitor in a implantable cardioverterdefibrillator which is adapted for implant in a patient, and which isalso adapted to deliver high voltage pulses to a patient in order topromote cardiac wellness. For example, in various embodiments, onemethod of the present invention includes providing a defibrillator casehaving circuitry disposed in the case. Additionally, various embodimentsinclude implanting an implantable cardioverter defibrillator in apatient. Also, some examples include connecting the cardiac system of apatient to the implantable cardioverter defibrillator. In one example,circuitry in the capacitor controls the discharge of electrical energyfrom the capacitor to the patient. Overall, in various embodiments, themethod of the present invention enables improved delivery of electricalstimulation to a patient using an implantable cardioverterdefibrillator.

Overall, the present subject matter offers multiple advantages. First,the present subject matter features capacitor designs which are compactand lightweight due to improved volumetric energy density. Smallercapacitors can enable smaller implantable medical devices, which tend toincrease patient comfort. Additionally, increasingly effectivecapacitors can do the work of two less effective capacitors, reducingsize and complexity of devices using capacitors. Reduced complexity canincrease reliability and reduce manufacturing costs.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. This application isintended to cover adaptations or variations of the present subjectmatter. It is to be understood that the above description is intended tobe illustrative, and not restrictive. Combinations of the aboveembodiments, and other embodiments, will be apparent to those of skillin the art upon reviewing the above description. The scope of thepresent subject matter should be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

1. A process, comprising: depositing a curable resin mask onto a foil;curing the curable resin mask into a cured mask; etching the foil, thecured mask restricting the etch; removing the cured mask from the foil;anodizing the foil; assembling the foil into a flat capacitor stack; andinserting the flat capacitor stack into a capacitor case.
 2. The processof claim 1, including connecting one or more electrically isolatedconductors connected to the capacitor stack; and filling the capacitorcase with an electrolyte; wherein the one or more electrically isolatedconductors sealingly extend outside the capacitor case.
 3. The processof claim 1, wherein assembling the foil into a flat capacitor stackincludes cutting the foil into shapes with a cutting tool, and stackingthe shapes into a capacitor stack, the cutting tool aligned using one ormore features for visual alignment printed onto the foil.
 4. The processof claim 1, wherein the curable resin mask is applied to a portion ofthe foil, and defines a grade between foil covered with curable resinmask and foil not covered with curable resin mask.
 5. The process ofclaim 4, including a second curable resin mask deposited on a secondside of the foil, the second curable resin mask defining a second gradebetween foil covered with curable resin mask and foil not covered withcurable resin mask.
 6. The process of claim 4, wherein the grade isshaped like a sinusoidal curve.
 7. The process of claim 4, wherein thegrade is shaped like a square wave.
 8. The process of claim 4, whereinthe grade includes a halftone.
 9. The process of claim 8, wherein thehalftone transitions from covering from about 80% of the grade tocovering about 60% of the grade.
 10. The process of claim 4, wherein thegrade is defined by a series of geometric shapes.
 11. The process ofclaim 10, wherein the shapes are approximately circular.
 12. The processof claim 1, wherein the curable resin mask is an ink.
 13. The process ofclaim 12, wherein the curable resin mask is deposited by a computercontrolled system adapted to selectively print a curable resin mask. 14.An apparatus, comprising: a case including material defining firstaperture sized for passage of the capacitor stack and a feedthroughhole; a capacitor stack disposed in the case, the capacitor stackincluding one or more substantially planar electrode layers, the one ormore substantially planar electrode layers having an etched surface, anunetched surface, and a grade bordering the etched surface and theunetched surface; a lid conforming to the first aperture and sealinglyconnected to the material defining the first aperture; a feedthroughassembly connected to the capacitor stack and passing through thefeedthrough hole and sealingly connected to the material defining thefeedthrough hole; and electrolyte disposed in the case; wherein the oneor more substantially planar electrode layers are made by printing acurable resin mask onto the one or more substantially planar electrodelayers and etching the layers, the curable resin mask defining the gradeand adapted to resist etching.
 15. The apparatus of claim 14, whereinthe grade is shaped like a sinusoidal curve.
 16. The apparatus of claim14, wherein the grade is shaped like a square wave.
 17. The apparatus ofclaim 14, wherein the grade includes a first portion defined by aplurality of shapes covering approximately 80% of the layer, and asecond portion defined by a plurality shapes covering approximately 60%of the layer.
 18. The apparatus of claim 17, wherein the shapes arecircular.
 19. The apparatus of claim 14, wherein the curable resin maskis an ink.
 20. The apparatus of claim 19, wherein the curable resin maskis deposited by a computer controlled system adapted to selectivelyprint a curable resin mask.